Secretary of State Antony J. Blinken said the United States believed China was considering supplying weapons and other lethal aid to Russia for its war in Ukraine and that he had warned Beijing that doing so “would cause a serious problem” for already strained relations with Washington.
The Biden administration has repeatedly warned Russia’s allies against providing military support for Moscow’s invasion of Ukraine. While the United States has so far only seen Beijing supply nonmilitary aid to Russia, “the concern that we have now is, based on information we have, that they’re considering providing lethal support,” Mr. Blinken told CBS News’ “Face the Nation” in an interview that aired on Sunday.
Mr. Blinken did not elaborate on what the United States believed China might supply, but said that it could include weapons and ammunition. The comments underscored concerns in the Biden administration that Moscow, heavily isolated by Western sanctions over its invasion, was increasingly turning to allies, including China, Iran and North Korea, for military supplies as its war approaches the one-year mark.
On Saturday, Mr. Blinken met with his Chinese counterpart, Wang Yi, at an annual security conference in Munich, the first high-level diplomatic exchange between the two sides since a Chinese spy balloon was found flying over the United States, causing a crisis in bilateral relations. A detailed readout of the meeting published by the Chinese state news agency Xinhua did not mention Russia or Ukraine.
But what American officials described as a testy encounter between the two diplomats highlighted how the war in Ukraine has become the latest point of friction between the United States and China. And it came at a Munich conference that was dominated by the war, with Western officials doubling down on their resolve to support Kyiv as Russia tries to step up a new offensive in eastern Ukraine.
The European Union’s top diplomat said on Sunday that Western nations must quickly increase their military support for Ukraine, rebuking the delays in providing weapons as the war enters what he called a “critical moment.”
The diplomat, Josep Borrell Fontelles, the E.U.’s foreign policy chief, told the gathering in Munich that praise and promises for President Volodymyr Zelensky of Ukraine were not enough. “There needs to be less applause and better supply with arms,” Mr. Borrell said, adding that “much more has to be done, and much quicker.”
Amid concerns over whether Western unity can endure as the war drags on, the United States and its European partners at the gathering sought to project resolve, largely repeating pledges to support Ukraine for as long as it takes. Mr. Blinken said he was “motivated by the accomplishments” allies have made in support of Ukraine, writing on Twitter on Sunday: “We will remain unified and see victory for Ukrainians fighting for their country’s fate.”
President Biden is scheduled to travel to Ukraine’s neighbor, Poland, to deliver a speech on Tuesday to observe the anniversary of Russia’s invasion. President Vladimir V. Putin of Russia is expected to deliver a speech on the same day.
With Russia trying to escalate an offensive in eastern Ukraine, Kyiv’s allies have been working to come up with ways to provide additional military support. After lengthy discussions, allies recently pledged to begin sending battle tanks to Ukraine, a decision that Mr. Borrell said had taken too much time.
“Everybody knows that in order to win a war” you need tanks, he told the conference.
Mr. Zelensky, in an opening address to the conference on Friday, warned his allies against “fatigue” and emphasized that speed was critical if his country were to hold off a renewed Russian onslaught. In an address late Saturday, Mr. Zelensky said that he was “grateful” for the “important statements” of support from Western officials in Munich.
“We received strong signals from our partners, and concrete agreements regarding the inevitability of holding Russia accountable for aggression, for terror against Ukraine and its people,” he said.
Russia responded sharply to Vice President Kamala Harris, who told the conference on Saturday that the United States had determined that Moscow had committed “crimes against humanity” in Ukraine and pledged to hold accountable “all those who have perpetrated these crimes,” as well as their superiors.
In a statement later Saturday, Anatoly Antonov, Russia’s ambassador to Washington, dismissed the comments “as an attempt, unprecedented in terms of its cynicism, to demonize Russia.”
Experts warn that any legal process to investigate and prosecute crimes against humanity would be long and tedious, with arrests or convictions far from assured. And while Mr. Zelensky’s allies have supplied Ukraine with ever more powerful weapons, it is not clear that his latest pleas — including for fighter jets and long-range missiles — will be met by Western leaders wary of provoking Russia into further aggression.
China, Russia’s most influential partner, delivered a typically calibrated message at the conference. Mr. Wang, China’s top diplomat, told the gathering that “nuclear wars must not be fought,” a potential signal to Moscow that China will not tolerate the use of nuclear weapons in Ukraine, as Russian officials have at times threatened.
At the same time, Mr. Wang sought to deflect blame for the war away from Russia, arguing that “some forces might not want to see peace talks” and “might have strategic goals larger than Ukraine itself.” That language echoed Kremlin claims, rejected by the West, that Moscow was willing to engage in good-faith peace talks and that NATO aimed to subjugate Russia.
Ukrainian officials have been warning of a potential Russian escalation timed to the first anniversary of the invasion and heavy fighting was reported Sunday around the city of Kreminna, a small but vital pocket of land in the Donbas region.
Serhiy Haidai, the head of the regional military administration, called the situation around Kreminna “difficult” and said shelling was constant. “Russians are trying to find a spot to penetrate our defenses,” he told Ukrainian television.
Elsewhere, Russian shelling killed a family of three people and wounded at least four other people in the southern region of Kherson, local officials said.
Edward Wong contributed reporting.















