US and Russian Presidents Donald Trump and Vladimir Putin would probably try to secure a ceasefire in Ukraine by one of two significant upcoming dates: Easter, which the Orthodox and Catholic churches will both celebrate on April 20 this year; or May 9, when Russia celebrates the Soviet victory over Nazi Germany, senior Ukrainian and Western officials said, reports Financial Times.

“Putin will want [a deal] on a notable day like this,” said a Ukrainian official.

Earlier, Russian presidential spokesperson Dmitry Peskov said that Moscow would be happy to welcome Donald Trump to the Victory Day celebrations on May 9—if he decides to come. According to Peskov, the presence of leaders of major countries in these celebrations will emphasize the importance of this date. Also, he recalled that Trump and Putin exchanged visit invitations the day before.

Putin’s main ambition, said people who have spoken to him during the war, is to establish a new security architecture that gives Russia a sphere of influence in Europe—much as the Yalta Conference did for the Soviet Union at the end of World War II.

“The situation looks much more favorable for Putin than at any point during the entire war over the last three years,” said Alexander Gabuev, director of the Carnegie Russia Eurasia Centre in Berlin. “If the US just unilaterally ends its military and diplomatic support, as well as intelligence sharing, then Ukraine will be in a very tough position. And it’ll be hard to get out of it even if the Europeans get more involved.”