As Iran retaliates, largest US military base in Middle East hit by ballistic missile, Qatar says

Eighteen U.S. service members have been seriously wounded as part of the military operation against Iran, according to CENTCOM spokesperson Capt. Tim Hawkins.

Earlier Monday, CENTCOM announced the death of a fourth U.S. service member. Two U.S. officials have told ABC News that the service member was killed in Sunday's attack in Kuwait.

At Monday morning’s Pentagon news conference, Joint Chiefs of Staff Chairman Gen. Dan Caine told reporters that the fatalities and injuries had come from an attack on a tactical operations center.

-ABC News' Luis Martinez

President Donald Trump said at the White House that he grieves for the four U.S. service members who have been killed.

“In their memory, we continue this mission with ferocious, unyielding resolve to crush the threat this terrorist regime poses to the American people,” he said.

“We have the strongest and most powerful -- by far -- military in the world, and we will easily prevail,” he said.

As for a timeline, Trump said the U.S. is “already substantially ahead of our time projections, but whatever the time is, it's OK.”

“From the beginning, we projected four to five weeks, but we have capability to go far longer than that,” he said.

“The United States military continues to carry out large-scale combat operations in Iran to eliminate the grave threats posed to America by this terrible, terrorist regime," President Donald Trump said Monday in his first public remarks since the strikes on Iran began Saturday.

Trump said Iran’s nuclear program was obliterated in "Operation Midnight Hammer," the U.S. strikes on Iran in June 2025. He said the U.S. “warned Iran not to make any attempt to rebuild at a different location, because they were unable to use the ones we so powerfully blew up.”

“But they ignored those warnings and refused to cease their pursuit of nuclear weapons,” Trump said at the White House. “In addition, the regime's conventional ballistic missile program was growing rapidly and dramatically, and this posed a very clear, colossal threat to America and our forces stationed overseas. The regime already had missiles capable of hitting Europe and our bases, both local and overseas, and would soon have had missiles capable of reaching our beautiful America."

"An Iranian regime armed with long-range missiles and nuclear weapons would be an intolerable threat to the Middle East, but also to the American people," he said. "Our country itself would be under threat, and it was very nearly under threat."

President Donald Trump did not rule out U.S. troops on the ground in Iran during an exclusive interview with the New York Post on Monday.

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

While the president told the Daily Mail on Sunday that the operation in Iran could take up to four weeks, the president on Monday told the New York Post that the operation is "going to go pretty quickly."

“We’re right on schedule, way ahead of schedule in terms of leadership -- 49 killed -- and that was, you know, going to take, we figured, at least four weeks, and we did it in one day,” Trump said, referring to the number of Iranian leaders he said were killed in the attacks on Iran.

-ABC News’ Michelle Stoddart