Defense Secretary Pete Hegseth on Monday laid out the Trump administration's objective for its joint air strikes with Israel on Iran: destroying the Middle East country's missile system and navy and ending its pursuit of a nuclear weapon.

"We didn't start this war, but under President Trump we are going to finish it," Hegseth said at the Pentagon, two days after the strikes began on Tehran." 

He also said the strikes were not for a "regime change," but he urged Iranians to take advantage of them killing Iran Supreme Leader Ayatollah Ali Khamenei and dozens of high-level government officials to try to install a new government. The strikes follow U.S. diplomats' efforts to reach an agreement with Tehran on how its nuclear program will go forward.

"This is not a so-called regime change war, but the regime has changed," Hegseth also said.

His remarks were the first on-camera by a Trump administration official since the strikes started Saturday.

The secretary was joined at the press briefing by Joint Chiefs of Staff Chairman Gen. Dan Caine who reiterated the U.S. mission was to "protect and defend" the United States and its allies.

"This was a massive and devastating attack" designed to "daze and confuse," he said.