The US president said he would "in all probability" speak with his Ukrainian and Russian counterparts as the two nations are at the brink of war.
US President Joe Biden said he is likely to speak to the leaders of Russia and Ukraine in an attempt to defuse growing tension over a Russian military build-up.
Biden answered ‘in all probability’ on Friday when asked by reporters if he would be speaking to Russian President Vladimir Putin or Ukraine's President Volodymyr Zelenskyy.
"I am concerned," he said, repeating his support for Ukraine's "territorial integrity."
The White House also urged diplomatic efforts to "de-escalate" tensions amid a Russian troop build-up on the Ukrainian border following Moscow's "harsh rhetoric."
Moscow, which backs separatist territories in eastern Ukraine and seized the Crimea region, has dismissed all accusations, blaming Kiev and Washington for raising tensions.
The US National Security Advisor, Jake Sullivan, talked with the head of the Ukrainian presidential administration, Andriy Yermak, said spokeswoman Emily Horne.
"They discussed their shared concerns about ongoing Russian military activities near Ukraine's border and its harsh rhetoric towards Ukraine. They agreed that all sides should pursue diplomatic efforts to de-escalate tensions," said Horne.
Horne also said that ‘Sullivan underscored the United States' unwavering commitment to Ukraine's sovereignty and territorial integrity’.
The call came as president Zelensky accused Russia of sending "very dangerous" signals on the border and said a coup plot involving Russian citizens had been uncovered in Ukraine.