According to the White House, President Joe Biden “reaffirmed unwavering U.S. support, including through continued security, economic, and humanitarian aid.” | Chip Somodevilla/Getty Images

President Joe Biden spoke with Ukrainian President Volodymyr Zelenskyy on Sunday, a day after Russian mercenary forces reversed their plans to march on Moscow, Zelenskky said. The White House confirmed the call on Sunday afternoon.

Zelenskyy and Biden discussed “the course of hostilities and the processes taking place in Russia,” Zelenskyy said in a post on Twitter. “The world must put pressure on Russia until international order is restored.”

Tensions between Russian leadership and the head of the Wagner mercenary group leader, Yevgeny Prigozhin, reached a boiling point over the weekend after Prigozhin accused the Russian military of firing on his forces and promised a “march of justice.” But by Saturday evening, Prigozhin had pulled back his forces, which he claimed had occupied the military command center at Rostov-on-Don, a major city in southern Russia.

Prigozhin was reported to have struck a deal with the Kremlin to leave Russia for Belarus, in exchange for Russia’s dropping criminal charges against him.

During their conversation, Biden and Zelenskyy also discussed “further expansion of defense cooperation, with an emphasis on long-range weapons,” as well as Ukraine’s air defense capabilities, Zelenskyy said.

According to the White House, the leaders discussed the tumult in Russia and Ukraine’s ongoing counteroffensive, and Biden “reaffirmed unwavering U.S. support, including through continued security, economic, and humanitarian aid.”