Ukraine’s Volodymyr Zelenskiy said on Tuesday that if U.S. President Joe Biden missed a peace summit organised by Kyiv in Switzerland next month, it would be like a standing ovation for Russian President Vladimir Putin.

Ukraine hopes to host as many countries as possible in an attempt to unite opinion on how to halt the war and pile pressure on Russia, which has seized almost a fifth of Ukraine’s territory. Washington has signalled support but has not said whether Biden will attend.

“I know that the U.S. supports the summit but we don’t know at what level,” the Ukrainian president said in Brussels on Monday at a joint press conference with Belgian Prime Minister Alexander De Croo.

“(The) peace summit needs President Biden and so do the other leaders who look at the reaction of the United States. His absence would be an applause to Putin, a personal standing applause to Putin.”

Zelenskiy on Sunday urged both Biden and Chinese President Xi Jinping, Putin’s close ally and a leading beneficiary of his rift to attend the summit.Russia, which launched a full-scale invasion of Ukraine in February 2022, has said it sees no point in the conference.