This was CNBC's live blog tracking developments on the war in Ukraine. See here for the latest updates. 

The Kremlin claimed Wednesday that Ukraine tried to strike the Kremlin with drones overnight but said the attack on the heart of the Russian government was "successfully repulsed."

Russian President Vladimir Putin was not injured in the purported attack, which was reported by Russian state media agency TASS on Wednesday. The Kremlin provided no evidence to back up the claim of an attempted attack, however.

Ukrainian officials denied any involvement in the alleged attack and said it might suggest Russia is planning a large-scale "terrorist" attack against Ukraine in the coming days.

The United States said it was unable to validate the Russian accusation.

In other news, Ukraine's President Volodymyr Zelenskyy made a surprise trip to Finland where he is meeting the country's president as well as other Nordic leaders for a summit on Wednesday.

Wheat rallies as future of the Black Sea Grain Initiative in jeopardy

Chicago wheat rebounded on Wednesday after hitting a 25-month low with escalating tensions between Russia and Ukraine further threatening the Black Sea grains deal, analysts told Reuters.

Corn also gained while soybeans fell as rapidly progressing U.S. planting weighed on prices.

Ukraine President Volodymyr Zelenskiy said Russia did not appear interested in extending the Black Sea grain deal, but that Kyiv was focused on looking for partners to fulfil the deal and was not looking for Russian interest. Talks were due to be held in Moscow on May 5, but it was unclear whether all parties were in agreement.

"It's a combo of being oversold, heavily short by the funds, the Russia Ukraine issue escalation, the tactic to negotiate the Black Sea and people coming out and saying the rains that happened in the Plains may not have helped the Kansas City wheat, that the damage is done," Craig Turner, commodities trader at Daniels Trading, told Reuters.

Favorable weather conditions across top suppliers — the United States, Russia and Europe — are driving hopes of ample supplies in the second half of 2023.

Ukraine's grain exports could fall to around 26 million tons in the coming season as harvest has sunk, largely due to Russia's invasion, a senior ministry official told Reuters.

—Joy-Marie Scott

US approves $300 million for Ukraine in latest security assistance package

The Biden administration approved a new security assistance package for Ukraine worth $300 million.

The latest military assistance package, the 37th such tranche, brings U.S. commitment to Ukraine's fight to more than $36 billion since Russia launched its full-scale invasion of Ukraine.

The capabilities in the package are:

• Additional ammunition for High Mobility Artillery Rocket Systems, or HIMARS
• 155mm Howitzers
• 155mm artillery rounds
• 120mm, 81mm, and 60mm mortar rounds
• Tube-Launched, Optically-Tracked, Wire-Guided, or TOW, missiles
• AT-4 and Carl Gustaf anti-armor weapon systems
• Hydra-70 aircraft rockets
• Small arms and small arms ammunition
• Demolition munitions for obstacle clearing
• Trucks and trailers to transport heavy equipment
• Testing and diagnostic equipment to support vehicle maintenance and repair
• Spare parts and other field equipment

— Amanda Macias

Two ships leave Ukrainian ports as expiration of Black Sea Grain Initiative looms

Two ships carrying 87,200 metric tons of wheat left Ukraine's ports of Chornomorsk and Odesa. The ships are destined for Spain and Bangladesh.

A day prior, no ships left Ukrainian ports under the Black Sea Grain Initiative. Ukraine's navy has previously said Russia suspends vessels from moving to and from Ukraine's ports.

Under the Black Sea Grain Initiative, which established a humanitarian sea corridor, more than 900 ships carrying more than 29 million metric tons of agricultural products have departed from Ukraine's war-weary ports. Russia has previously said that it would not recognize an extension of the deal, which could expire in mid-May.

— Amanda Macias

Russian strike in Kherson region kills 16 civilians

EDITORS NOTE: This post contains graphic content and graphic images of death and destruction from a Russian missile strike.

Sixteen civilians were killed Wednesday in heavy Russian shelling of Ukraine's Kherson region, according to Reuters.

Ukrainian officials said the Russian missile strike hit a large store, a railway station and residential buildings.

Twelve of the victims were in the city of Kherson, the southern region's capital, where a large retail center known as hypermarket came under fire as people were in the store shopping, Reuters reported.

The news agency said explosions also tore through a railway station in the area and that at least two survivors were seen being carried out on stretchers.

Four more people — including three engineers who were trying to repair the power grid that has been damaged in earlier Russian bombardments — were killed in villages outside the main city.

Ukrainian officials said 22 people had also been wounded in Kherson city in "chaotic shelling and strikes on civilian infrastructure facilities."

Russia did not comment on the attacks in Kherson, one of four Ukrainian regions it said it annexed last September.

Read the full report from Reuters here.

— Michele Luhn

Biden issues statement in support of detained journalists on World Press Freedom Day

President Joe Biden said his administration would continue to support newsrooms and journalists around the world in a statement on World Press Freedom Day.

"No journalist – American or not – should have to risk their lives and livelihoods in pursuit of that truth. Evan Gershkovich and Austin Tice weigh heavy on my mind today," Biden said.

"A free press is a pillar of democracy. It allows our government and our society to be self-critical and self-correcting. It educates, illuminates, exposes, and uncovers. It serves as a guardian of truth," he added.

Gershkovich, a reporter for The Wall Street Journal based in Moscow, was arrested more than a month ago by Russian authorities on espionage charges.

Tice, a freelance journalist and former U.S. Marine, was kidnapped in Syria in 2012 and ahs been held captive since.

— Amanda Macias

Blinken says U.S. cannot validate accusation that Ukraine attempted to kill Putin

U.S. Secretary of State Antony Blinken on Wednesday said the U.S. cannot validate Russia's accusation that Ukraine tried to strike the Kremlin with drones overnight in an attempt to assassinate Russian President Vladimir Putin, according to Reuters.

Blinken said he would take anything coming from the Kremlin with a "very large shaker of salt," according to the report.

He also reiterated the United States' support for Ukraine and said he feels confident that the country will be successful in its effort to retake more of its territory.

— Michele Luhn

State Department announces potential weapons sale worth $110 million to Latvia

The U.S. State Department has approved a potential foreign military sale to Latvia for a naval strike missile coastal defense system, as allies look to bolster their borders amid Russia's war in Ukraine.

The system and related equipment will cost an estimated $110 million.

The proposed sale will improve Latvia's current capability to deter threats in the Baltic Sea and will contribute to U.S. security interests.

"This proposed sale will support the foreign policy goals and national security objectives of the United States by improving the security of a NATO ally that is a force for political stability and economic progress in Europe," the State Department wrote in a statement announcing the sale.

— Amanda Macias

Ukraine denies any involvement in alleged Kremlin drone attack

Ukraine denied any involvement in an alleged drone attack on the Kremlin that Moscow has blamed on Kyiv.

A senior Ukrainian presidential official, Mykhailo Podolyak, said Ukraine had nothing to do with the drone strike, stating on Twitter that "Ukraine wages an exclusively defensive war and does not attack targets on the territory of the Russian Federation."

Rather, he said the allegations suggest Russia was planning a large-scale "terrorist" attack against Ukraine in the coming days.

Serhii Nikiforov, Ukrainian President Volodymyr Zelenskyy's spokesman, also told the Ukrainian Pravda news outlet that Kyiv was not involved in the incident.

"We have no information about the so-called night attacks on the Kremlin, but as President Zelenskyy has repeatedly stated, Ukraine directs all available forces and means to liberate its own territories, not to attack foreign ones," he told the news outlet in comments translated by NBC News.

Nikiforov said Russia's description of the incident as a "terrorist" attack was interesting given Russia's repeated attacks against Ukrainian territory over the course of the war.

"A terrorist attack is the destroyed houses in Dnipro and Uman, or a rocket fired at the train station in Kramatorsk and many other tragedies. And what happened in Moscow was obviously an escalation of the situation in light of May 9," alluding to Russia's upcoming Victory Day parade commemorating the Soviet victory over Nazi Germany in World War II.

The comments come after the Kremlin claimed Wednesday that Ukraine tried to strike the Kremlin with drones overnight, but said the purported attack on the heart of the Russian government was "successfully repulsed."

Russian President Vladimir Putin was not injured in the incident, the Kremlin said. It provided no evidence to back up the claim of an attempted attack.

— Holly Ellyatt

Russia claims Ukraine tried to strike the Kremlin with drones

The Kremlin claimed Wednesday that Ukraine tried to strike the Kremlin with drones overnight but said the attack on the heart of the Russian government was "successfully repulsed."

Russian President Vladimir Putin was not injured in the purported attack, which was reported by the Kremlin, which provided no evidence to back up the claim of an attempted attack, however.

"Last night, the Kyiv regime attempted to strike the Kremlin residence of the President of the Russian Federation with unmanned aerial vehicles," the Kremlin stated, with the claim detailing that "two unmanned aerial vehicles were aimed at the Kremlin."

"As a result of timely actions taken by the military and special services with the use of radar warfare systems, the devices were disabled," the Kremlin said.

"As a result of their fall and the scattering of fragments on the territory of the Kremlin, there are no casualties and material damage."

Putin was not injured and continues to work as usual after the Kyiv attack, it said.

The Kremlin's statement suggested that it viewed the attempted attack as a "planned terrorist action" and an attempt on the life of the president ahead of Victory Day on May 9.

Russia was already believed to be slimming down its Victory Day parade, which commemorates the Soviet Union's victory over Nazi Germany in WW2, amid fears of Ukrainian strikes.

Russia reserves the right to respond to an attempt to strike at the Kremlin where and when it sees fit, the Kremlin added, without giving details on how it planned to respond.

Footage began circulating on social media channels purportedly showing what could be an unmanned aerial vehicle appearing to explode above a domed roof of one of the Kremlin's buildings. CNBC wasn't able to immediately verify the authenticity of the footage, however.

Ukraine has not publicly commented on the claims. NBC News has reached out to the Ukrainian government for comment but hasn't yet received a response.

— Holly Ellyatt

Huge fires caused at Ukrainian and Russian oil depots after drone attacks

Oil facilities in Ukraine and Russia have been targeted in separate incidents reportedly involving drones.

Ukrainian officials said a Russian drone strike on an oil depot in the city of Kropyvnytskyi, in the central Kirovohrad region of Ukraine, had caused a major fire. Andriy Raykovych, the head of the Kirovohrad regional military administration, said Russia had used drones to attack the facility during the night.

"Around three in the morning, 3 Geran-2 [Iranian-made Shahed-136 drones] bombers attacked an oil depot in the regional center at once. There were no casualties," he said on Telegram, adding that emergency services were on the scene. Ukraine's prosecutor general said that as a result of the drone attack, a "large-scale fire started."

Meanwhile, it's believed that a major fire that broke out Wednesday at a fuel depot in a village in the southwestern Russian region of Krasnodar, near the Crimean bridge linking the Russian mainland to the Crimean peninsula annexed by Russia in 2014, was also caused by a drone.

"The fire of a tank with oil products on the territory of the JSC Tamanneftegaz enterprise occurred as a result of the fall of a drone," TASS reported, citing the emergency services which said a fire had broken out covering almost 1.25 thousand square meters. "Extinguishing is currently ongoing. There are no casualties," the representative of the emergency services said.

Reuters reported that rail deliveries to Russia's nearby Black Sea port of Taman would be restricted until further notice.

The news agency reported that videos from Taman posted on Russian social media showed flames and black smoke billowing over large tanks emblazoned with red lettering reading "flammable." Reuters could not independently verify either the fire reports or the videos, however.

The latest incident comes after Moscow accused Ukraine of setting fire to an oil depot in Sevastopol in Crimea last weekend.

Ukraine's military command did not take direct responsibility for the attack but an official noted that the undermining of Russia's logistics were part of "preparatory" work ahead of its anticipated counteroffensive.

— Holly Ellyatt

Suspect in killing of Russian war blogger says she was set up

A woman accused of assassinating a prominent Russian military blogger has said she is "insanely sorry" for delivering the bomb that killed him, but that she did not know the true content of the parcel she handed him in a St Petersburg cafe a month ago.

Darya Trepova is now in detention in Moscow on terrorism charges, accused of cooperating with Ukrainian special services to kill Maxim Fomin, who wrote a popular pro-war blog under the name Vladlen Tatarsky.

"Most of all I want to die," the 26-year-old told the St Petersburg online news channel Rotonda, which posted extracts of its interview online.

"I replay the events over and over in my head ... Why did I simply believe that there was nothing dangerous in the package that I was asked to deliver?" she was quoted as saying.

"The most unbearable thing is that they killed a man with my hands, and maimed dozens. I have always been against violence."

Trepova did not say who had asked her to present the package — a bust of Tatarsky, with explosives concealed inside — to the blogger as he was meeting other supporters of the war.

Having survived the blast, she said she had written herself a letter in prison to convince herself that she should not take her own life.

"I'm insanely sorry for what happened," Trepova said. "I pray for the health of the victims and will try to organise a collection of funds to help the victims of the tragedy recover."

Now in the Lefortovo prison, often used for those suspected of spying and other grave crimes, Trepova said she had been visited three or four times by investigators, but had not yet been allowed to see a lawyer. Rotonda did not say when the interview had been given.

— Reuters

Zelenskyy makes surprise trip to Finland

Ukrainian President Volodymyr Zelenskyy is in Finland on Wednesday, marking the latest in a series of rare trips outside Ukraine for the president.

Zelenskyy will meet Finnish President Sauli Niinisto and other Nordic leaders gathered at the presidential palace for talks, according to Finnish news agency STT.

Finland is holding the Nordic-Ukraine summit today and Niinisto and Zelenskyy will be joined by Swedish Prime Minister Ulf Kristersson, Norwegian Prime Minister Jonas Gahr Store, Danish Prime Minister Mette Frederiksen and Icelandic Prime Minister Katrín Jakobsdottir.

The war, Nordic support for Ukraine and the country's relationship with the EU and NATO will be on the agenda for talks. At the end of the discussions, a joint press conference will be held, the news agency said.

— Holly Ellyatt

Russia's FSB says 7 Ukrainian agents arrested in Crimea

Russia's Federal Security Service (FSB) said on Wednesday it had arrested seven people connected with Ukrainian intelligence and accused them of planning "a series of high-profile sabotage and terrorist acts" in Russian-annexed Crimea.

In a statement, the FSB said the group had planned attacks against Russian-installed officials including local governor Sergei Aksyonov. It said it had seized explosives identical to those used to attack railways in the peninsula in February.

In a statement, Aksyonov said the same group was behind both alleged incidents. He said, without providing evidence, that there was no doubt that the Ukrainian government was behind them.

Russia seized Crimea from Ukraine in 2014 and used it as one of the launchpads for its full-scale invasion of Ukraine in February 2022.

Separately on Wednesday, Russian emergency services blamed a large fire at a fuel depot on the Taman peninsula, which adjoins Crimea across the Kerch strait, on a drone falling on the facility.

— Reuters

Russian forces could be shifting focus away from Ukraine's power network

Russian forces could be shifting their attacks away from Ukraine's energy network, Britain's Ministry of Defense said Wednesday.

Remarking on recent air-launched cruise missile (ALCM) attacks carried out by Russia on April 28 and May 1, the ministry noted that the observed types of facilities damaged by the Russian strikes indicated "a possible shift away from targeting Ukraine's electrical power network" and instead a focus on the country's military, industrial and logistical infrastructure.

The strikes were the first such strikes for 50 days, with the last prior strikes occurring on March 9.

"The latest strikes were conducted by Russian Long Range Aviation strategic bombers, both Tu-95 and Tu-160 aircraft, likely using Kh-101 and Kh-555 ALCMs," the ministry said.

"Both strikes used smaller numbers of missiles than seen in previous attacks, which is likely due to Russian attempts to rebuild its ALCM stockpiles," it added.

— Holly Ellyatt

Meeting on grain export deal arranged for May 5, minister says

The deputy defense ministers of Russia, Ukraine and Turkey are due to meet in Istanbul on May 5 to discuss the extension of the Black Sea Grain Initiative, according to Turkey's Defense Minister Hulusi Akar.

"It is planned that the deputy ministers of defense of Turkey, Ukraine and Russia will meet in Istanbul on Friday, May 5," Akar said, according to Turkish news agency Anadolu.

As it stands, the grain deal, which has enabled millions of tons of Ukrainian agri-food products to leave the country via several ports, expires on May 18. Russia has said there are no guarantees it will agree to extend the deal.

Akar said Turkey hoped the grain deal would continue without any disruption.

"This agreement is very important for the countries in need as well as for regional peace and stability. In this context, we can say that the parties look forward to the extension of the [deal]. Our wish is to extend this initiative without any problems," he said, according to a Google translation of the comments.

— Holly Ellyatt

Ukraine's capital Kyiv targeted by Russian drones overnight

Kyiv was targeted by Russian forces again last night, marking the third time in six days that the capital has been targeted.

An air raid alert went off in the capital and a number of regions overnight Wednesday because of a Russian drone attack, according to Serhiy Popko, head of the Kyiv city military administration.

Posting on Telegram, Popko said Kyiv was being attacked with Iranian "Shahed" drones, a weapon that has become a staple for Russian forces in the war.

"The capital of Ukraine suffered another air attack from the enemy. The third time in the past 6 days! This time Kyiv was attacked by drones only," Popko said on Telegram.

"The tactics of the enemy remain usual and unchanged - with the onset of darkness, the terrorist country launched its barrage of ammunition from various directions," Popko said.

According to preliminary information, the drones were shot down in the airspace above the capital with no reports of injuries or damage.

Ukraine's Air Force Command said on Facebook that its defense forces had destroyed 21 of 26 Russian Shahed-136/131 type one-way attack drones overnight. The drones had been launched from both the north, from the Bryansk region in Russia and to the north of Ukraine, and the south, from the eastern coast of the Sea of Azov.

— Holly Ellyatt

No ships leave Ukrainian ports as expiry of Black Sea Grain Initiative looms

No ships carrying agricultural products left Ukrainian ports under the Black Sea Grain Initiative as the deal faces expiry. Ukraine's Navy has previously said Russia suspends vessels from moving to and from Ukraine's ports.

Three ships carrying 119,925 metric tons of agricultural products left Ukraine's ports of Chornomorsk and Odesa on Monday. The ships are destined for China, Morroco and The Netherlands.

Under the Black Sea Grain Initiative, a humanitarian sea corridor, more than 900 ships carrying nearly 29 million metric tons of agricultural products have departed from Ukraine's war-weary ports. Russia has previously said that it would not recognize an extension of the deal, which could expire in mid-May.

— Amanda Macias

Ukraine and allies working to block Russian efforts to circumvent sanctions, Zelenskyy says

Ukrainian President Volodymyr Zelenskyy said that his country, along with its allies, is preparing "a large sanctions package" in a nightly address.

"We are closely monitoring how the terrorist state is trying to circumvent sanctions, recording each such direction, and working together with our partners to block it," Zelenskyy said referencing Russia.

"We are preparing a large sanctions package. The decision will be made soon," he said, without adding additional details.

Since Russia's invasion of its ex-Soviet neighbor, Washington and allied countries have imposed rounds of coordinated sanctions vaulting Russia past Iran and North Korea as the world's most-sanctioned country.

— Amanda Macias

China needs to be more 'tough-minded' on Russia, says U.S. ambassador

U.S. Ambassador to China Nicholas Burns said on Tuesday that China needs to push Russia to withdraw its troops from Ukraine.

Burns, speaking by video link with the Stimson Center think tank in Washington, D.C., added that a recent phone call from China's Xi Jinping to Ukrainian President Volodymyr Zelenskyy was "a good first step," but he doesn't know if China has offered to be a meditator between the two countries.

"China has a very close relationship with Russia, a supportive relationship with Russia," he noted. "Certainly, we'd like to see China be much more tough-minded in its advice to the Russians, and we'd like to see action to end the war as quickly as possible in terms, of course, that the Ukrainian government can accept."

He also said that the U.S. has been warning China not to provide lethal military assistance to Russia, and officials have seen no evidence that the Chinese are doing so.

— Michele Luhn

Kremlin rejects U.S.' Russian casualty claims

The Kremlin rebuffed U.S. intelligence suggesting Russia had suffered around 100,000 casualties in the past five months of fighting in Ukraine, mostly in the east of the country.

Kremlin Press Secretary Dmitry Peskov told reporters Tuesday that the data was "taken from nowhere."

"Washington simply does not have the possibility to name any correct figures, they do not have such data. And that is how it should be treated. You should rely only on the data published by the Ministry of Defense of Russia," he said.

Peskov's comments come after White House national security spokesperson John Kirby told reporters Sunday that U.S. intelligence estimated that Russia had seen 100,000 casualties in recent months and that the figure included 20,000 dead, half of them from the Wagner mercenary group.

— Holly Ellyatt

Putin warned he could be arrested if he attends BRICS summit

Russian President Vladimir Putin was warned he could be arrested if he attends a BRICS (Brazil, Russia, India, China, and South Africa) summit in South Africa in August.

Authorities in the country warned that they would be compelled to detain the president after a warrant for his arrest issued in March by the International Criminal Court in The Hague.

South Africa's Sunday Times newspaper, citing sources in the country's government, said that a special government commission established by South African President Cyril Ramaphosa to look into the international arrest warrant concluded that the country would have no choice but to arrest Putin if he traveled to South Africa for the summit.

"We have no option not to arrest Putin," a government official told The Sunday Times. "If he comes here, we will be forced to detain him."

Putin was expected to travel to the summit, although the Kremlin had not confirmed his attendance, to meet with the leaders of BRICs.

The newspaper reported that officials were trying to find a way around the diplomatic dilemma, with Putin's "virtual" attendance via videolink being mooted as a possible workaround.

The paper's sources said that "the only option we have is for [Putin] to participate in the summit via Teams or Zoom from Moscow."

— Holly Ellyatt

Read CNBC's previous live coverage:

Putin warned of arrest if he attends summit; Kremlin rejects U.S. claim of 100,000 Russian casualties