In his first public sermon in eight years, Iran’s supreme leader Ayatollah Ali Khamenei, 80, told tens of thousands of chanting worshipers on Friday that God’s backing had allowed his country to “slap the face” of the U.S. “We delivered a slap to U.S.’ image as a superpower.”

Khamenei spoke at Tehran’s Grand Mosalla, an indoor and outdoor complex used as a communal prayer center for Muslim holidays and as an arena for election campaigns. American flags were spread on the floor in the entrances so that worshipers could tread on them. Banners inside read, “Death to America.”