Russia’s Foreign Ministry on Thursday warned the United States against launching military action against Iran, as tensions escalate in the Middle East and speculation grows over potential U.S. involvement in the conflict alongside Israel.

Israel launched airstrikes on Iran’s military and nuclear program last Friday, and Tehran has responded with its own salvos of rockets and drones. Scores of civilians have been killed in both countries since the air war began, and despite global calls for de-escalation, the two sides have ramped up their bellicose rhetoric.

U.S. President Donald Trump has further fueled tensions by suggesting earlier this week that American forces in the Middle East might try to assassinate Iran’s Supreme Leader Ayatollah Ali Khamenei and vaguely calling on Tehran to agree to an “unconditional surrender.”

“We would like to particularly warn Washington against military intervention in this situation,” Russian Foreign Ministry spokeswoman Maria Zakharova said Thursday.

Zakharova noted that any such move by the U.S. “would be an extremely dangerous step with truly unpredictable negative consequences.”