Washington —The recent attack on Saudi oil facilities was approved by Iran's supreme leader, Ayatollah Khamenei, but only on the condition that it be carried out in a way that made it possible to deny Iranian involvement, a U.S. official told CBS News.

Saudi Arabia on Wednesday displayed wreckage of what it said were Iranian cruise missiles and drones. The circuit boards can be reverse engineered to determine the exact route the weapons flew. But U.S. officials said the most damning evidence is still unreleased satellite photos showing the Iranian Revolutionary Guard making preparations for the attack at Ahvaz Air Base in southwestern Iran.

From there, the weapons flew through Kuwaiti airspace some 400 miles to their targets in Saudi Arabia. The satellite photos were of no use in stopping the attack since their significance was not realized until after the fact. "We were caught completely off guard," one U.S. official said.

A picture taken on September 18, 2019, shows displayed fragments of what the Saudi defense ministry spokesman said were Iranian cruise missiles and drones recovered from the attack site that targeted Saudi Aramco's facilities. Fayez Nureldine / AFP/Getty

The Saudis showed grainy surveillance video of the incoming Iranian drones but none of the actual detonations that one U.S. official described as "a tidal wave of flame." Secretary of State Mike Pompeo, who met with Saudi Arabia's crown prince, called it an "act of war." But President Trump said he's in no rush to respond.

"There's plenty of time to do something dastardly things. We'll see what happens," he said.

General Frank McKenzie, the top U.S. military commander for the Middle East, has asked permission to send three more batteries of anti-aircraft missiles to help Saudi Arabia protect its oil facilities. McKenzie has also drawn up plans for retaliatory strikes against Iranian oil facilities and the Iranian Revolutionary Guard.

When President Trump was briefed on the military options, he insisted Saudi Arabia would have to contribute to any retaliatory strike. He's scheduled to meet again with his national security advisors on Friday.