WASHINGTON

US Defense Secretary Pete Hegseth on Monday said that the operation against Iran is not intended to topple the country’s leadership, even as he acknowledged the sweeping impact of the operation.

"This is not a so-called regime change war, but the regime sure did change," Hegseth told a news conference alongside Chairman of the Joint Chiefs of Staff Gen. Dan Caine.

His remarks came after the US and Israel launched strikes against Iran on Feb. 28, killing the country's Supreme Leader Ali Khamenei and other top security officials.

"The mission of Operation Epic Fury is laser-focused. Destroy Iranian offensive missiles, destroy Iranian missile production, destroy their navy and other security infrastructure, and they will never have nuclear weapons," Hegseth said.

He added that Iran was building "powerful" missiles and drones to create a "conventional shield for their nuclear blackmail ambitions."

Hegseth also said this would not be an "endless" war.

“This is not Iraq. This is not endless.”

'We expect to take additional losses'

The secretary refused to outline a timetable for the conflict, stating that the duration of military operations against Tehran would ultimately be determined by US President Donald Trump.

"President Trump has all the latitude ... to talk about how long it may or may not take, four weeks, two weeks, six weeks, it could move up. It could move back," he said.

He also said there are no US boots on the ground in Iran.

"No, but we’re not going to go into the exercise of what we will or will not do,” he said, leaving the door open.

The US "would go as far as we need to go," Hegseth said.

Caine, for his part, said US Central Command (CENTCOM) received the final go order from Trump on Friday at 15:38 Washington time.

Providing a step-by-step account of the opening phase of Operation Epic Fury, Caine said more than 100 aircraft launched from land and sea in a synchronized wave.

‘Massive, overwhelming attack’

"This was a massive, overwhelming attack across all domains of warfare," Caine said, adding the US struck more than 1,000 targets in the first 24 hours.

"This is not a single overnight operation. The military objectives that CENTCOM and the Joint Force have been tasked with will take some time to achieve, and in some cases will be difficult and gritty work," he added.

CENTCOM announced Monday that four US service members have been killed in action as US-Israeli joint attacks enter their third day.

"We expect to take additional losses, and as always, we will work to minimize our losses. But as the Secretary said, This is major combat operations," Caine said.

Earlier, CENTCOM said that three US F-15E Strike Eagles flying in support of the operation went down over Kuwait due to an "apparent friendly fire incident."

Caine said he is "grateful" for the safety of the crews.

"We know that this was not from hostile enemy fire, as this matters under investigation, I'll not comment further on this," he added.

Caine said it will take some time for the Pentagon to conduct a battle damage assessment.

The flow of forces to the region continues, the general said.

"I don't want to talk because that would tip the enemy off," Caine said when asked how many troops are involved in the operation, and additional troops are planned to go.