President Donald Trump said the U.S. imposed sanctions on Iran’s central bank in retaliation for last weekend’s attacks on Saudi Arabia’s key oil facilities.

“These are the highest sanctions ever imposed,” Trump told reporters during a meeting with Australian Prime Minister Scott Morrison at the White House on Friday. “We’ve never done it at this level.”

Treasury Secretary Steven Mnuchin said the move would cut off funding for the Islamic Revolutionary Guard Corps. It’s a controversial step, as sanctioning the central bank may also limit the ability to import humanitarian goods into the country.

The Treasury Department hasn’t issued a statement about the sanctions and spokesmen for the agency didn’t immediately respond to requests for comment.

Trump said he’ll meet Friday with his national security advisers to discuss further responses to the attack on the Saudi oil facilities, which the U.S. has blamed on Iran. He’s under pressure from hawks among congressional Republicans to order a military attack on the Islamic Republic but has resisted, and has drawn comparisons to the Iraq War that he says he opposed.

Trump said a U.S. attack would be the “easiest thing,” adding, “and maybe it’s even a natural instinct.” But he said that he was showing U.S. strength by not immediately ordering a strike. He could take out 15 different targets in Iran if he wanted to, Trump said.

“I could do it right here, in front of you, and that would be it,” he said. “It shows far more strength to do it the way we’re doing it. I think restraint is a good thing.”