Russian President Vladimir Putin is drawing up plans to invade neighbouring Ukraine in 2022, the US Government has warned.
US President Joe Biden will hold crisis talks with the Russian premier tomorrow amid concerns of a large build up of troops, artillery and tanks at its western flank, The Times reports.
American intelligence officials predict the Kremlin may launch an attack into Ukrainian territory in the new year.
Satellite images of the area shows up to 175,000 soldiers poised for war at the edge of Europe, experts believe.
Moscow's deployment of reserve forces to 50 battle groups on the field has also caused concern.
But Russian officials say the gathering of soldiers and weapons is part of a routine military exercise and accused Kiev and Nato of stoking aggression.
Fourteen thousand people have died since the conflict in Ukraine's eastern Donbas region started in 2014.
After the main crisis, the two parties became locked in stalemate, but intermittent violence often spills over in the form of shellings and skirmishes.
Putin has previously stated western sanctions will never force a change of course with regards to Ukraine.
On Friday, President Biden threatened Moscow with tough financial sanctions which will "make it very, very difficult for Mr Putin".
US Secretary of State Anthony Blinken added that measures could be "high-impact" and of the type they've "refrained from taking in the past".
A White House statement said Biden would discuss US concerns about the border enforcement and "reaffirm" support for the Ukrainian government.
It said: "President Biden will underscore US concerns with Russian military activities on the border with Ukraine and reaffirm the United States' support for the sovereignty and territorial integrity of Ukraine."
The US has estimated that there are 70,000 troops on the border, but Ukraine claims the number is significantly higher at 94,000.
In addition to the large build up of forces, the US believes a renewed propaganda campaign in Russia-aligned media outlets in Ukraine suggest groundwork for an invasion is being laid.
Russian foreign ministry official, Maria Zakharova, said: "Russian armed forces on Russian territory is the legal right of a sovereign state. The US media should be concerned by the aggressive activity of the US, not Russia."
At the end of last month, Russia warned the UK of a "serious risk" of conflict after Britain announced plans to send an armoured brigade back to Germany - a decade after bringing troops home from the EU nation.
Russia has accused the UK of moving closer to its territory.
Allied nations have responded by issuing declarations of solidarity with the Kiev government.
At the time, Russia's UK ambassador, Andrei Kelin, warned of a "pretty serious risk" of war between the two countries.
