The assistance suggests the rapidly expanding war now includes the involvement of one of Washington’s key nuclear-armed rivals with advanced intelligence capabilities, The Caspian Post reports, citing The Washington Post.

Since the conflict began on Saturday, Russia has reportedly shared the locations of U.S. military assets with Iran, including warships and aircraft, the officials said. They spoke on condition of anonymity because of the sensitivity of the issue.

The Russian Embassy in Washington did not respond to requests for comment.

Moscow has previously called for an end to the war, describing it as an “unprovoked act of armed aggression.”