Membership in the alliance is one of the stumbling blocks in US-led efforts to end the four-year war -- a conflict that US President Donald Trump had pledged to settle within a day of returning to office.

Kyiv views membership in NATO as a bulwark against a future Russian assault, while Russian President Vladimir Putin mentioned the expansion of NATO as one of the reasons for sending troops to Ukraine.

The topic was "one of the key questions, it was discussed," between Putin, US envoy Steve Witkoff and Trump's son-in-law Jared Kushner, top Kremlin aide Yuri Ushakov said.

"The American partners have confirmed their readiness to take into account our considerations and our key proposals," Ushakov told journalists, including from AFP, during a briefing.

Trump has repeatedly ruled out Ukraine's NATO membership, and his latest 28-point plan, which critics said was a Russian wish list, explicitly stated that Kyiv would never be admitted to the alliance.

The plan was later amended by Ukraine and Europe, but Moscow appeared to reject it at the meeting on Tuesday.

NATO chief Mark Rutte on Wednesday said that the door remained open for Kyiv's membership, but added that currently "there is no consensus on Ukraine joining NATO".

NATO foreign ministers were set to discuss the US push to stop the fighting at a meeting in Brussels on Wednesday -- but US Secretary of State Marco Rubio is skipping the gathering.