U.S. Secretary of State Marco Rubio said on Wednesday that Russia has pledged to send Washington its terms for a ceasefire in Ukraine.

“It’s our understanding that the Russians are going to write up terms for what they would require in order to reach a ceasefire that then would allow broader negotiations. We await those terms and then we’ll have a much better understanding about Mr. Putin’s calculation once we see what those terms look like,” Rubio said during a Senate Foreign Relations Committee hearing on May 20, as quoted by Politico.

The Secretary of State added that the U.S. would be prepared to impose sanctions on Russia if it becomes clear that “the Russians are not interested in a peace deal and they want to keep fighting a war,” according to the Financial Times. Rubio also noted that President Donald Trump “wants to preserve as long as he possibly can the opportunity to influence both sides towards peace.”

Commenting on the Russia–Ukraine talks held in Istanbul on May 16, the secretary of state called it a positive step that both sides had agreed to a prisoner exchange based on a “1,000-for-1,000” basis. Still, Rubio said that “what we haven’t seen yet is moves toward peace.”