U.S. President Joseph Biden, in a telephone conversation with Ukrainian President Volodymyr Zelensky on Sunday evening, assured of the readiness of the U.S. and its allies to give a decisive response to possible aggression from Russia, the White House said in a statement.

"President Joseph Biden Jr. spoke today with Ukrainian President Volodymyr Zelensky. President Biden made it clear that the U.S., its allies and partners will respond decisively if Russia further invades Ukraine," the press release said.

The leaders expressed support for diplomatic efforts, which will begin next week with a bilateral dialogue on strategic stability, in NATO through the NATO-Russia Council and in the Organization for Security and Cooperation in Europe.

At the same time, Biden stressed the commitment of Washington, allies and partners to the principle of "nothing about you without you." He also reaffirmed the U.S.' commitment to the sovereignty and territorial integrity of Ukraine.

Biden expressed support for "confidence-building measures to de-escalate tensions in Donbas and active diplomacy to advance the implementation of the Minsk agreements in support of the Normandy format."