WASHINGTON, APR 14 – U.S. President Joe Biden emphasized the United States’ unwavering commitment to Ukraine’s sovereignty and territorial integrity in a phone call with Russian President Vladimir Putin on Tuesday, and called on Russia to de-escalate tensions, the White House said.

Biden expressed concern about Russia’s military buildup in the Crimea region of Ukraine and on Ukraine’s border, the White House said in a statement.

It said Biden also made clear that the United States will act “firmly” to defend its national interests in response to Russia’s actions, such as cyber intrusions and election interference. Biden also proposed holding a summit with Putin in a third country in coming months.