UN says more than 8,400 killed in Ukraine since war's start; more revelations emerge from leaked Pentagon documents

President Joe Biden spoke with the family of detained Wall Street Journal reporter Evan Gershkovich reporter from Air Force One.

"We appreciate President Biden's call to us today, assuring us that the U.S. government is doing everything in its power to bring him home as quickly as possible," Gershkovich's family said in a statement that was shared by Dow Jones, the parent company of the Wall Street Journal.

"There is a hole in our hearts and in our family that won't be filled until we are reunited. We are grateful for the outpouring of support from his colleagues, friends and everyone standing with Evan and advocating for his immediate release."

Earlier on Tuesday, Biden told reporters that he had previously tried to call Gershkovich's family on Monday.

Gershkovich was arrested last month on allegations of espionage. The State Department formally moved to declare Gershkovich's detention a wrongful one, which opens up additional resources to secure his release.

— Amanda Macias

Three ships carrying 62,460 metric tons of barley and sunflower meal left Ukraine's ports of Chornomorsk.

The vessels are destined for China.

The Black Sea Grain Initiative, a deal brokered in July between Ukraine, Russia, Turkey and the United Nations, eased Russia's naval blockade and reopened three key Ukrainian ports. Ukraine and the UN pushed for a 120-day extension of the deal in March but Russia agreed to only 60 days, which would expire in May.

So far, more than 750 ships have sailed from Ukrainian ports since the deal launched.

— Amanda Macias

Ukrainian Foreign Minister Dmytro Kuleba spoke to U.S. Secretary of State Antony Blinken and provided an update on the war.

Kuleba said that Blinken "reaffirmed the ironclad U.S. support" for Ukraine during their phone call.

"The U.S. remains Ukraine's trustworthy partner, focused on advancing our victory and securing a just peace," Kuleba wrote on Twitter.

The State Department did not immediately provide a readout of the call between Blinken and Kuleba.

The call comes on the heels of a leak of highly classified Pentagon documents that contained sensitive information on Ukraine's strategy on the battlefield, among other intelligence.

The White House has previously said that the U.S. has been in contact with relevant allies and partners about the matter.

National Security Council spokesman John Kirby said the leaked intelligence, which has not been identified as authentic, would not impact U.S. assistance to Ukraine.

— Amanda Macias

Treasury Secretary Janet Yellen condemned the detention of Wall Street Journal reporter Evan Gershkovich and said the matter is critical for the Biden administration.

She declined to say whether the U.S. would consider imposing sanctions or other economic measures on Russia in response to Gershkovich's detention when asked during a press conference at the Department of Treasury.

Earlier in the day, President Joe Biden said he tried to call Gershkovich's family on Monday but was unable to reach them. He told reporters on the White House lawn that he would attempt to call Gershkovich's parents again from Air Force One.

"We're making it real clear that it's totally illegal what's happening and we declared it so. It changes the dynamic," Biden said.

— Amanda Macias

The Hungarian government — which has lobbied to be exempted from any European Union sanctions imposed on Russian gas, oil or nuclear fuel — signed new agreements for continued access to Russian energy, the Associated Press reported.

Hungarian Foreign Minister Peter Szijjarto said Russian state energy company Gazprom agreed to allow the import of natural gas beyond the amounts agreed to in a long-term contract that was amended last year.

Most members of the 27-nation bloc have distanced themselves from Russian President Vladimir Putin and have sought to wean their countries off of Russian fossil fuels, the AP reported.

— Melodie Warner

Senate Majority Leader Chuck Schumer, D-N.Y., requested a classified briefing for all senators on the leaked classified U.S. documents pertaining to Ukraine.

The date and time for the briefing has not been set yet, according to a spokesman for Schumer.

The White House said the highly classified Pentagon documents that were leaked last week will not impact U.S. security and intelligence assistance to Ukraine.

The documents, which were circulated online, contained sensitive information on Ukraine's strategy on the battlefield, among other intelligence matters.

— Amanda Macias

The United Nations has confirmed 8,490 civilian deaths and 14,244 injuries in Ukraine since Russia invaded its ex-Soviet neighbor a year ago.

The Office of the U.N. High Commissioner for Human Rights said the death toll in Ukraine is likely higher, because the armed conflict can delay fatality reports.

The international organization said most of the civilian casualties recorded were caused by the use of explosive weapons with a wide impact area, including shelling from heavy artillery and multiple launch rocket systems, as well as missiles and airstrikes.

— Amanda Macias

Australia's defense chief called the recent leak of U.S. intelligence files a serious incident, emphasizing the issue of trust between partners.

"The issue of maintaining security of information is critical to the development of national capability and to the trust and confidence across allies and partners," Angus Campbell, the head of the Defence Force of Australia, said during an event at the country's Lowy Institute.

The leaked documents, the veracity of which CNBC is not able to confirm, are likely real, according to a senior U.S. official cited by NBC News. Officials warn however that some of the files may have been altered.

Based on the government's working theory, which is pending investigation, the leak is considered to be the most serious breach of U.S. intelligence in years.

— Natasha Turak

Treasury Secretary Janet Yellen will discuss additional ways to enforce sanctions and economic measures against Russia for its war in Ukraine during the International Monetary Fund and World Bank spring meetings this week in Washington.

"Over the past year, our campaign has systematically degraded Russia's military-industrial complex and helped reduce the revenues that Russia can use to fund its war," Yellen will tell reporters, according to a preview of her remarks.

"This year, a central piece of our strategy is to take further actions to disrupt Russia's attempts to evade our sanctions," the preview added.

Yellen will also applaud the IMF's recent $15.6 billion loan program for Ukraine and discuss the challenges facing the global economy due to the war in Ukraine.

— Amanda Macias

Wagner Group boss Yevgeny Prigozhin has political ambitions that he is advancing, Russian opposition outlet Meduza reports.

The head of Russia's infamously brutal private military organization has had a very public falling out with the Russian state defense establishment, as he vocally criticizes its performance in the Ukraine war and accuses it of sidelining and sabotaging his group.

"Two Kremlin sources and one St. Petersburg government insider claimed that Prigozhin is pursuing a leadership position within [political party] A Just Russia — For Truth's St. Petersburg branch to compete with St. Petersburg Governor Alexander Beglov for influence in the city," the think tank Institute for the Study of War wrote.

ISW cited Meduza in its daily update, saying that the outlet's sources "claimed that Prigozhin previously was interested in investing in the 'Motherland' political party and may be interested in pursuing a position at the federal level."

Wagner is believed to have at least 50,000 men fighting on the ground in Ukraine, many of them convicts. The group has been accused of war crimes.

— Natasha Turak

The Biden administration is working to mend ties among some key allies who are upset over revelations from recently leaked U.S. intel documents.

U.S. Defense Secretary Lloyd Austin held a phone call with South Korea's defense minister, after lawmakers in Seoul were angered over reports of the CIA spying on their discussions about arms sales to Washington.

"If the report is true, it would be an action that can never be acceptable between allies of 70 years, and an infringement of sovereignty and diplomatic foul play that breaks bilateral trust head-on," Park Hong-keun, the leader of South Korea's Democratic party, told local media on Monday.

Another report from the leak is a purported CIA update from early March saying that Israel's intelligence agency, Mossad, encouraged its officers to join local protests against controversial reforms being pushed by the Israeli government. The Israeli administration denied Mossad had any part in the protests.

— Natasha Turak

Russian forces are continuing to make gains in the destroyed eastern Ukrainian city of Bakhmut after months of bloody fighting, the Institute for the Study of War reported.

"Russian forces continued to make territorial gains in and around Bakhmut on April 9 and 10 but likely continue to suffer significant casualties. Geolocated footage posted on April 9 and 10 shows that Russian forces made marginal advances northwest of Khromove (2km west of Bakhmut), in southwest Bakhmut, and north of Sacco i Vanzetti (15km north of Bakhmut)," the institute wrote in its daily update.

Russian Airborne forces have started appear in Bakhmut "likely to reinforce conventional, rather than Wagner Group, forces," it wrote, adding that a Ukrainian commander said that "Ukrainian forces have exhausted Wagner forces so much that the Russian military command has had to send SPETSNAZ and VDV elements to Bakhmut."

— Natasha Turak

Ukrainian Prime Minister Denys Shmyhal has landed in Canada for an official visit, during which he will request more aid and ammunition for Ukraine's anticipated counteroffensive, according to local reports.

"Now, we need heavy armoured vehicles. And we need more artillery shells: ammunition for howitzers and ammunition for tanks," Shmyhal told Canadian newspaper The Globe and Mail in an interview. "It's crucially important for the organization of our counteroffensive."

In a tweet, Shmyhal wrote that meetings with Canadian Prime Minister Justin Trudeau and Deputy Prime Minister Chrystia Freeland are coming up, and that "We are preparing new agreements and deals to strengthen the macro-financial and economic stability of [Ukraine]. We are working for victory."

Canada has been a consistent backer of Ukraine and is home to a large Ukrainian diaspora community.

— Natasha Turak

More information has come out of the leaked U.S. intelligence documents that began surfacing online last week.

One document detailed by the Washington Post purports to describe a conversation between Egyptian President Abdel Fatah El-Sisi and his top military officials — in it, Sisi directs officials to keep certain rocket exports and production hidden "to avoid problems with the west" and discusses plans to send Russia gunpowder and other ammunition

Asked for comment by the Post, a spokesperson for Egypt's foreign ministry said that "Egypt's position from the beginning is based on noninvolvement in this crisis and committing to maintain equal distance with both sides, while affirming Egypt's support to the UN charter and international law."

The leaked files — the veracity of which CNBC is not able to confirm — are likely real, according to a senior U.S. official cited by NBC News. Officials warn however that some of the files may have been altered.

— Natasha Turak

The U.S. military document leak is an opportunity to recalibrate our understanding of what is happening in Ukraine, said a political science professor at Harvard University.

Graham Allison, Harvard's Douglas Dillon professor of government, said the Ukrainian government has said its military is "killing ten times as many Russians as Russians are killing Ukrainians." But the intelligence leak suggests, instead, that there are four times as many Ukrainians killed, he told CNBC's "Squawk Box Asia."

"It's one of the rare occasions where you can study the differences between what is being said in public and ... what the realities are on the battlefield," he added.

A senior U.S. official previously told NBC News that the leaked documents are likely real, but some may have been altered before they were posted.

The classified documents that surfaced on social media last week include details on Ukraine's air defenses and plans for a spring offensive against Russian troops. Allison called this a "big loss" for Ukraine, as information about its air defenses "make it possible for Moscow to bring its aircraft and bombers back into the fight."

"The order of battle of your enemy ... [is] one of the most valuable things that an adversary can have," he said.

— Audrey Wan

The U.S. State Department officially declared that journalist Evan Gershkovich is being wrongfully detained in Russia, NBC News reported.

This designation means that the WSJ reporter's case will now be handled by the Office of the Special Presidential Envoy for Hostage Affairs and gives the government other resources to work on freeing him.

"Journalism is not a crime," State Department spokesperson Vedant Patel said in a statement. "We condemn the Kremlin's continued repression of independent voices in Russia, and its ongoing war against the truth."

Gershkovich was arrested on spying allegations in Russia.

— Riya Bhattacharjee

State Department designates Evan Gershkovich wrongfully detained by Russia; U.S. grapples with fallout from intelligence leak