KYIV, Ukraine — Prime Minister Fumio Kishida made a surprise visit Tuesday to Kyiv, stealing some of the attention from Asian rival President Xi Jinping of China, who met in Moscow with Russian President Vladimir Putin to promote Beijing’s peace proposal for Ukraine that Western nations have already criticized.

The two visits, about 500 miles apart, highlighted the nearly 13-month-old war’s repercussions for international diplomacy as countries line up behind Moscow or Kyiv. Kishida, who will chair the Group of Seven summit in May, met President Volodymyr Zelenskyy and paid tribute to those killed in Bucha, a town outside Kyiv that became a symbol of Russian atrocities against civilians.

After talks with Xi, Putin said a Chinese peace plan could provide a basis for a settlement of the fighting in Ukraine when the West is ready for it, but he added that Kyiv’s Western allies have shown no interest in that.

U.S. officials have said any peace plan coming from the Putin-Xi meeting would be unacceptable because a cease-fire would only ratify Moscow’s territorial conquests and give Russia time to plan for a renewed offensive.

“It looks like the West indeed intends to fight Russia until the last Ukrainian,” Putin said, adding the latest threat is a British plan to give Ukraine tank rounds containing depleted uranium.

“If that happens, Russia will respond accordingly, given that the collective West is starting to use weapons with a nuclear component,” he said, without elaborating.

Putin has occasionally warned that Russia would use all available means, including possibly nuclear weapons, to defend itself, but also has sometimes backed off such threats.

Putin’s comment referred to remarks Monday by U.K junior Defense Minister Annabel Goldie, who wrote: “Alongside our granting of a squadron of Challenger 2 main battle tanks to Ukraine, we will be providing ammunition, including armor-piercing rounds which contain depleted uranium. Such rounds are highly effective in defeating modern tanks and armored vehicles.”

Russian Foreign Minister Sergey Lavrov said the U.K. plan shows that the British “have lost the bearings,” and Defense Minister Sergei Shoigu said “it marked another step, and there aren’t so many of them left.”

But weapons expert Hamish de Bretton-Gordon, former commander of Britain’s Royal Tank Regiment, said it was “reckless” of Putin “to try and suggest Britain is sending nuclear material” to Ukraine. He said depleted uranium is a common component of tank rounds, possibly even used by Russia.

“Putin insinuating that they are some sort of nuclear weapon is bonkers,” de Bretton-Gordon told The Associated Press. “Depleted uranium is completely inert. There is no way that you could create a nuclear reaction or a nuclear explosion with depleted uranium.”

Beijing insists it is a neutral broker in Ukraine, and Xi said Tuesday after his talks with Putin: “We adhere to a principled and objective position on the Ukrainian crisis based on the goals and principles of the U.N. Charter.” He added that the Chinese plan seeks to “actively encourage peace and the resumption of talks.”

In a joint statement, Russia and China emphasized the need to “respect legitimate security concerns of all countries” to settle the conflict, echoing Moscow’s argument that it sent troops into its neighbor to prevent the U.S. and its NATO allies from turning the country into an anti-Russian bulwark.

“Russia welcomes China’s readiness to play a positive role in the political and diplomatic settlement of the Ukrainian crisis” and the “constructive ideas” contained in Beijing’s peace plan, the statement said. It added: “The parties underline that a responsible dialogue offers the best path for a lasting settlement … and the international community should support constructive efforts in this regard.”

After meeting Kishida, Zelenskyy told reporters his team had sent his own peace formula to China but hasn’t gotten a response, adding that there were “some signals, but nothing concrete about the possibility of a dialogue.”

Kishida called Russia’s invasion a “disgrace that undermines the foundations of the international legal order.”

Earlier he laid flowers at a church in Bucha for the town’s victims.

“Upon this visit to Bucha, I feel a strong resentment against cruelty,” he said. “I would like to represent the people in Japan, and express my deepest condolences to those who lost their loved ones, were injured as a result of this cruel act.”

U.S. Ambassador to Japan Rahm Emanuel noted the “two very different European-Pacific partnerships” that unfolded Tuesday.

“Kishida stands with freedom, and Xi stands with a war criminal,” Emanuel tweeted, referring to Friday’s decision by the International Criminal Court to issue an arrest warrant for Putin, saying it wanted to put him on trial for the abductions of thousands of children from Ukraine.

Kyiv’s allies pledged more support. Washington is accelerating its delivery of Abrams tanks to Ukraine, sending a refurbished older version that can be ready faster, U.S. officials told The Associated Press.