According to the White House, US President Joe Biden has warned that there is a “clear chance” that Russia could attack Ukraine next month.
Meanwhile, since the US rejected Russia’s primary requests, Russia sees “no reason for confidence” in resolving the problem.
In recent weeks, the presence of tens of thousands of Russian troops near Ukraine’s borders has fuelled concerns of an invasion.
Russia denies that such strike is in the works.
On Thursday, Trump made the remarks during a phone discussion with Ukrainian President Volodymyr Zelensky.
“President Biden has stated that the Russians may attack Ukraine in February,” according to White House National Security Council spokesman Emily Horne.
“He has openly said this, and we have been warning about it for months.”
President Biden “reaffirmed the United States’ readiness, together with its friends and partners, to respond strongly if Russia continues to occupy Ukraine,” according to a White House statement.
They “discussed recent diplomatic efforts on de-escalation and agreed on collaborative initiatives for the future,” according to Mr Zelensky.
According to Axios, which cited anonymous sources, the two differed on the severity of the danger. According to some military analysts, Russia may be waiting for the ground in Ukraine to freeze so that heavy equipment can be sent in.
On Friday, French President Emmanuel Macron will talk directly with Russian President Vladimir Putin in another significant phone call.
It would not be the first time that Russia invaded Ukraine. In 2014, Russia annexed Ukraine’s Crimea peninsula in the south. It also backed separatists who took huge swaths of the eastern Donbas region shortly after, killing over 14,000 people in the process.
On Thursday, the United States threatened to cancel the construction of a vital pipeline that would transport Russian gas to Western Europe if Russia invaded Ukraine.
Nord Stream 2 would flow from Russia to Germany, and Berlin authorities cautioned on Thursday that if Russia attacks, the project might face penalties.
Western partners have stated that if Russia invades, they will strike its economy, and the recent remarks indicate a tightening of their attitude.
The pipeline, which runs for 1,225 kilometers (760 miles), took five years to develop and cost $11 billion (£8 billion). The energy project, which would run beneath the Baltic Sea, aims to increase Russia’s gas supplies to Germany by a factor of two.
However, it has yet to begin operations, since regulators stopped its permission in November after determining that it did not conform with German law.
Russia denies any invasion intentions, but issued broad security demands of the West last month, including that Ukraine never be included to the Nato military alliance.
The US turned down this major demand, instead providing Moscow a “real diplomatic road ahead.”
On Thursday, Kremlin spokesperson Dmitry Peskov said the US reaction provided “little room for hope,” but added that “there are always opportunities for maintaining a discussion, it’s in both our and the Americans’ interests.”
The suggestions will not be made public, but US Secretary of State Antony Blinken said the memo outlined their “fundamental values,” which include Ukraine’s sovereignty and the freedom to choose whether or not to join security alliances like Nato.
The formal answer, according to Russia’s foreign minister Sergei Lavrov, does not address Russia’s “primary worry” about the alliance’s development.