The latest sanctions layer on top of a slew of other penalties the Trump administration has imposed and reimposed as a result of Trump’s unilateral withdrawal from a 2015 nuclear deal with Iran and other world powers. The existing sanctions have already targeted Iran’s oil exports, its metal and mining industries and its ability to receive financing from international banks. Tehran has repeatedly likened the sanctions to “economic warfare.”

The new sanctions will affect “the last remaining source of funds for both the central bank of Iran, as well as the national development fund — which is their sovereign wealth fund,” Treasury Secretary Steven Mnuchin told reporters Friday. “This is very big — we’ve now cut off all source of funds to Iran.”

The new sanctions indicate Trump is unlikely to back down from a maximum pressure campaign designed to force Tehran back to the negotiating table with the U.S., which has long accused Iran of bad behavior in the Middle East, including funding groups designated by Washington as terrorist organizations.

Trump sidestepped a question at a press conference later Friday when asked whether the sanctions on Iran’s national leave the U.S. without any breathing room to further escalate its pressure campaign without moving beyond economic penalties.

“These are the strongest sanctions ever put on the country. We are at a level of sanctions that is far greater than ever before, with respect to Iran,” he reiterated, arguing that Iran has “a lot of self-made problems.”

He added: “Iran could be a great country, a rich country. But they are choosing to go a different way.”

Iranian President Hassan Rouhani has said repeatedly that relief from U.S. sanctions would be a precondition for any meeting between himself and Trump.

The president first forecasted a new round of penalties in a tweet this week, though he did not provide any specifics at the time.

The drone strikes, which took place overnight last Saturday, disrupted half of Saudi Arabia’s oil supply and the daily equivalent of 5 percent of the world’s oil supply. Iranian-backed Houthi rebels in neighboring Yemen have maintained that they are responsible for the strikes, though some U.S. officials, like Secretary of State Mike Pompeo, have blamed Iran for the attacks from the outset.

Throughout the week, Trump has been more hesitant to directly blame Iran, though he’s alluded to it multiple times. Saudi Arabia also took longer to publicly blame Tehran, citing the need to finish investigating the strikes, but it too finally accused Iran of carrying out the attacks later in the week.

Iran has denied any culpability for the attack and warned the U.S. that a military response will spark an “all-out war” and immediate retaliation from Tehran.

Trump has increasingly leaned against responding militarily despite asserting over the weekend and throughout the week that the U.S. was “locked and loaded” and could attack at any time.

Under fire from Iran hawks in Congress over his manner of responding to the strikes, he defended his decision to go the sanctions route, contending that a retaliatory attack would, in fact, be “the easiest thing I could do.”

“It’s so easy. For all of those that say they should do it, it shows weakness, it shows — actually, in my opinion it shows strength because it’s the easiest thing I could do — OK, go ahead, knock out 15 different major things in Iran,” the president said with a shrug. “I could do that. All set to go. It’s all set to go. But I’m not looking to do that if I can.”

Trump maintained that his new sanctions did not preclude him from military action, nor did he say that such a move was off the table.

But “I think the strong person’s approach, and the thing that does show strength would be showing a little bit of restraint,” he argued. “Much easier to do it the other way. It’s much easier. And Iran knows if they misbehave they are on borrowed time.”

The Associated Press reported Friday that Pentagon officials are set to offer Trump an array of possible responses to the attack. At the White House hours later, the president punted when asked by a reporter whether he was weighing any other non-military options in the event that Iran continues to lash out and stir up conflict in the region, and would not elaborate on possible alternatives.

“I don’t want to talk about that,” Trump said. “But I will say I think the sanctions work, and the military would work, but that is a very severe form of winning. But we win. Nobody can beat us militarily. No one can even come close.”