"Ukraine's membership in NATO would have very, very negative consequences for the entire security architecture in Europe, which is already half destroyed," Kremlin spokesman Dmitry Peskov said.

He added that Kyiv's membership in the Western military bloc would represent "an absolute danger and a threat to our country" that would call for a "firm" response from Moscow. He did not elaborate.

NATO leaders meet in Lithuania on Tuesday for a summit set to be dominated by the alliance's response to Russia's assault on Ukraine and Kyiv's push for membership.

Ukrainian President Volodymyr Zelensky has said he does not expect Ukraine to actually join NATO until after the conflict but he hopes the summit will give a "clear signal" on the intention to bring Ukraine into the alliance.

Russian leader Vladimir Putin has repeatedly raged about NATO's eastward expansion, accused NATO members of taking part in the Ukraine conflict by donating arms to Kyiv and said the West planned to break up Russia.