Russia said Sunday that it “strongly condemned” the United States’s bombings of nuclear sites in Iran, calling the attacks “irresponsible” and a “gross violation of international law.”

“It is already clear that a dangerous escalation has begun, fraught with further undermining of regional and global security,” the Russian Foreign ministry added in a statement.

The United States struck three nuclear sites in Iran on Sunday, joining Israel’s bombing campaign after days of speculation over U.S. involvement in the conflict.

“Iran’s key nuclear enrichment facilities have been completely and totally obliterated. Iran, the bully of the Middle East, must now make peace,” President Donald Trump said in an address after the strikes.

Iran’s Foreign Minister Abbas Araghchi condemned the U.S. attacks as “outrageous” and said his country had a right to defend its sovereignty.

“The events this morning are outrageous and will have everlasting consequences,” he posted on social media, calling the attacks “lawless and criminal” behaviour.

Araghchi later said the United States and Israel crossed “a very big red line” with the attacks, and said he would head to Moscow later Sunday for talks with President Vladimir Putin.