The Kremlin said Monday that U.S.-Russia relations were on the brink of collapse and refused to confirm whether Russian President Vladimir Putin had spoken with President Donald Trump, despite Trump saying so Sunday.

Russian Deputy Foreign Minister Sergei Ryabkov told a media conference Monday that relations with Washington “are balancing on the brink of a breakup” and reiterated that the war in Ukraine would last until Kyiv drops its ambitions to join NATO and withdraws from the four regions occupied by Russian forces.

In remarks suggesting Moscow is maintaining its tough negotiating stance, Ryabkov said that “we simply imperatively need to get … the new U.S. administration to understand and acknowledge that without resolving the problems that are the root causes of the crisis in Ukraine, it will not be possible to reach an agreement.”

Kremlin spokesperson Dmitry Peskov said the same day that he would “neither confirm nor deny” Trump’s comments to reporters on Air Force One on Sunday that he and Putin had spoken in his first officially acknowledged contact with the Russian leader since 2022.

Referring to his contact with the Russian leader, Trump told reporters, “let’s just say I’ve had it … and I expect to have many more conversations. We have to get that war ended.”

“I hate to see all these young people being killed. The soldiers are being killed by the hundreds of thousands,” he said, but declined to provide any more details about how many times the two had spoken, responding, “I’d better not say.”

The remarks from Trump and spokespeople for the Kremlin come at a crucial juncture for the war in Ukraine, with Kyiv and its European neighbors nervously awaiting details of Trump’s peace plan to end the conflict that Russia launched with its full-scale invasion three years ago.

Between winning election in November and being inaugurated last month, Trump said he planned to end the war in a single day upon taking office.

Referring to Trump’s remarks Sunday, Keir Giles, a senior fellow of the Russia and Eurasia Program at the London think-tank Chatham House, said “it would be tempting to think that this was all part of a careful plan for not releasing information too early in order not to bridge this process.”

“Or it could simply be that, as seems to be the case with Trump’s earlier promises of immediate action to bring the conflict to an end, that there isn’t, in fact, a plan yet,” he told NBC News.

Giles added that more clarity on the situation may come later this week, with Ukrainian President Volodymyr Zelenskyy due to attend the high-profile Munich Security Conference, which senior U.S. officials are also attending.

Trump’s national security adviser, Mike Waltz, told NBC News’ “Meet the Press” on Sunday that the U.S. officials would be “talking through the details of how to end this war and that will mean getting both sides to the table.”

He added that Trump would be “prepared to tax, to tariff, to sanction” Moscow to get Putin to the negotiating table, while also stripping back assistance to Ukraine to force European allies to ramp up support to Ukraine.

Ryabkov’s comments today came after Zelenskyy told the British broadcaster ITV last week that he was ready to hold talks with Russia as long as “I had an understanding that America and Europe will not abandon us and they will support us and provide security guarantees.”

The Ukrainian leader also told Reuters on Sunday that it was important he meets Trump before any negotiations with Putin, “otherwise, it will look like a dialogue about Ukraine without Ukraine.”

A Russian drone attack on Kyiv late Sunday injured a woman and damaged several houses in the northeastern city of Sumy, Ukrainian officials said Monday.

Astha Rajvanshi

Astha Rajvanshi is a reporter for NBC News Digital, based in London. Previously, she worked as a staff writer covering international news for TIME.