Moscow and Kiev have agreed to abide by a "ceasefire" policy during talks in the Normandy format in Paris. After nearly 9 hours of talks, Paris officials described the discussions as a "good signal".
The gathering of Russian troops near the border with Ukraine has raised fears that the Kremlin is planning an invasion of its neighbor Ukraine.
The United States warned Moscow on Tuesday of damaging sanctions, including measures personally targeting Vladimir Putin, as Russian combat troops massing around Ukraine launched new exercises.
Tension appeared to be only increasing, with the White House saying the risk of a Russian invasion of Ukraine "remains imminent."
The Security Service of Ukraine (SSU) said on Tuesday that it had "uncovered a Russian criminal group" that planned to carry out a "series of armed attacks" on the country's territory.
The SSU claims that the group is "coordinated by the Russian special services" and that its goal was to work to "destabilize" Ukraine.
Russia's eventual attack on Ukraine will provoke a fierce response, NATO Secretary General Jens Stoltenberg announced last night.
"We have agreed that any new Russian aggression against Ukraine will have serious consequences," Stoltenberg said on Twitter after an online meeting with Biden and the leaders of France, Germany, Italy, Poland, Great Britain and the EU, Reuters reports.