Russia cannot accept US proposals to end the war in Ukraine in their current form because they do not address problems Moscow regards as having caused the conflict, a senior Russian diplomat said, suggesting US-Russia talks on the subject had stalled.

The comments by Deputy Foreign Minister Sergei Ryabkov suggest Moscow and Washington have so far been unable to bridge differences which President Vladimir Putin raised more than two weeks ago when he said US proposals needed reworking.

They come as US President Donald Trump appears to be growing increasingly impatient with what he has suggested might be foot-dragging over a wider deal by Moscow.

Trump in recent days has said he is “pissed off” with Putin and has spoken of imposing sanctions on countries that buy Russian oil if he feels Moscow is blocking a deal.

Ryabkov, a specialist in US-Russia relations, said Moscow was not yet able to move forward with a deal, however.

“We take the models and solutions proposed by the Americans very seriously, but we can’t accept it all in its current form,” Ryabkov was quoted by state media as telling the Russian magazine “International Affairs” in an interview released on Tuesday.

“As far as we can see, there is no place in them today for our main demand, namely to solve the problems related to the root causes of this conflict. It is completely absent, and that must be overcome.”

Putin has said he wants Ukraine to drop its ambitions to join NATO, Russia to control the entirety of four Ukrainian regions it has claimed as its own, and the size of the Ukrainian army to be limited.

Kyiv says those demands are tantamount to demanding its capitulation.

Asked about Trump’s latest remarks about wanting Putin to do a deal on Ukraine, Kremlin spokesman Dmitry Peskov told reporters earlier on Tuesday that Moscow was “continuing our contacts with the American side”.

The European Union has a “strong plan” to retaliate against tariffs imposed, and set to be imposed, by Donald Trump.

“The subject is very complex. The substance that we are discussing, related to the Ukrainian settlement, is very complex. This requires a lot of extra effort.”

Before the weekend, Trump had adopted a more conciliatory stance towards Russia that had left Western allies wary as he tried to broker an end to the conflict in Ukraine, now in its fourth year.

But in recent days and amid lobbying by Europeans such as Finland’s president urging him to hold Russia to account, he has adopted a tougher tone.