Top American officials said on Monday that a Russian invasion of Ukraine remained imminent amid continued troop movements, propaganda and bellicose language from Moscow, suggesting that prospects are dim for a summit between President Biden and President Vladimir V. Putin in the days ahead.

Jake Sullivan, Biden’s national security adviser, said on NBC’s Today Show that the President is willing to “go the extra mile on diplomacy”, but added that “every indication we see on the ground right now in terms of the disposition of Russian forces is that they are in fact getting prepared for a major attack on Ukraine”.

Putin ratcheted up tensions further on Monday morning during a meeting of his Security Council, announcing that he would decide by day’s end whether to recognise two breakaway Ukrainian regions as independent states. At the same time, Russian media broadcast claims of assaults by Ukrainian forces, charges that Ukrainian military leaders forcefully denied.

American officials have repeatedly predicted that the Russian military would stage false attacks on their own forces as a way of providing Putin a pretext to go to war.

Biden agreed “in principle” on Sunday to a proposal by President Emmanuel Macron of France for a summit with Putin. But numerous White House officials said that such a meeting in the coming days was “notional” at best, and would not happen if Russian forces cross the border into Ukraine.

Two senior officials said on Monday that there had been no change in that thinking overnight, and that there have been no discussions about the format, timing or location for such a meeting.