The United States will impose "severe economic harm" on Russia and boost its military presence in Eastern Europe should Moscow invade Ukraine, the White House warned Monday, laying out the high stakes on the eve of talks between US President Joe Biden and Russian President Vladimir Putin.

The US president will also quickly inform his Ukrainian counterpart Volodymyr Zelensky of the details of his discussion with Putin, taking place by videoconference Tuesday as tens of thousands of Russian troops were positioned near the Ukraine border, a senior US official told reporters.

The United States and its European allies are prepared to take "substantial economic countermeasures that would impose significant and severe economic harm on the Russian economy" if Russia attacks, the official revealed.

In addition, Biden will make clear that if Putin "moved in, there would be an increasing request from eastern flank allies and a positive response from the United States for additional forces and capabilities and exercises."

The US official mentioned that Biden will be speaking Monday with key European allies to coordinate their stances, and that Secretary of State Antony Blinken would also talk to Zelensky beforehand.

Asked if the United States was prepared to send troops into Ukraine if Russia attacks, the official confirmed they are "not seeking to end up in a circumstance in which the focus of our countermeasures is the direct use of American military force."

The Kremlin said earlier Monday that Moscow is not expecting "breakthroughs" from the call.