Any U.S. attack on Iran will be met with a massive loss of life by American forces, senior Iranian military commanders warned on Sunday.

The semi-official Fars news agency quoted Gen. Gholamali Rashid as backing his country’s military prowess, warning Washington “should behave in a responsible way to protect the lives of American forces.”

Gen. Rashid said if hostilities happen against the Islamic republic, its scope and duration could not be controlled, and blamed any escalation in the Middle East on “U.S. interventionist policy.”

The general oversees and coordinates joint military operations in the Iranian Armed Forces.

His words of warning were echoed by the commander of the Islamic Revolutionary Guard Corps (IRGC), Major General Hossein Salami, who told Washington officials to leave Iran alone.

“Borders are our red lines and any enemy which violates them will not go back home and will be annihilated. The only way for enemies is to respect Iran’s territorial integrity and national interests,” Salami said.

Iran’s warnings against any U.S. intervention came as it was revealed the U.S. launched a cyber attack against Iranian spy assets in the hours after the Islamic republic downed an American navy reconnaissance drone last week.

U.S. Cyber Command was behind the retaliatory strike against the spy group, which has ties to the (IRGC).