WASHINGTON, United States (AFP)—United States President Donald Trump on Monday said he is not ruling out sending US troops into Iran, while threatening a new, “big wave” of attacks.

The 79-year-old Republican has long campaigned against decades of US military entanglements in the Middle East, but ordered a large-scale war against Iran starting Saturday.

While so far the assault has focused entirely on aerial attacks by missiles and bombs, Trump refused to rule out sending ground troops — something generally considered to be far riskier in terms of possible casualties.

“I don’t have the yips with respect to boots on the ground — like every president says, ‘There will be no boots on the ground.’ I don’t say it,” Trump told the New York Post in one of numerous brief interviews he has given since launching the Iran operation.

“I say ‘probably don’t need them,’ [or] ‘if they were necessary,'” he said.

Trump also spoke to CNN on Monday, flagging what he said would be an escalation in the assault on Iran.

“We haven’t even started hitting them hard. The big wave hasn’t even happened,” he told CNN, without elaborating. “The big one is coming soon.”

US and Israeli forces have so far struck hundreds of targets across Iran, including the Islamic republic’s missiles, navy and command-and-control sites.

Four US military members have been announced killed and three fighter jets have been shot down — officially in friendly fire.

Iran has fired missiles at Israel, at US bases around the region and also at targets in regional Arab countries — Bahrain, Jordan, Kuwait, Qatar and the United Arab Emirates — something that Trump called “the biggest surprise.”

– Two, four, six weeks? –

Trump’s comments came shortly after Defense Secretary Pete Hegseth also signaled that deploying troops inside Iran had not been ruled out.

Asked if there were already boots on the ground, Hegseth told a news conference: “No, but we’re not going to go into the exercise of what we will or will not do.”

“We’ll go as far as we need to go,” he said.

As for how long the war will last, Hegseth said: “Four weeks, two weeks, six weeks, it could move up. It could move back.”

He sought to differentiate the Iran operation from past long-running US wars in Iraq and Afghanistan, saying the war is not an effort to build democracy in Iran.

“No stupid rules of engagement, no nation building quagmire, no democracy-building exercise. No politically correct wars. We fight to win and we don’t waste time or lives,” the Pentagon chief said.

“This is not Iraq. This is not endless,” Hegseth said. “Our generation knows better and so does this president. He called the last 20 years of nation building wars ‘dumb’ and he’s right.”

General Dan Caine, the top US military officer, spoke alongside Hegseth, saying that air superiority had been achieved over Iran.

Strikes by American forces “resulted in the establishment of local air superiority. This air superiority will not only enhance the protection of our forces, but also allow them to continue the work over Iran,” Caine said.