President Donald Trump defended the expanding U.S. military campaign against Iran on Sunday, insisting Tehran has "lost everything, almost, militarily," before abruptly ending a question-and-answer session with reporters at Joint Base Andrews after being challenged about the duration of the conflict and the recent deaths of three American service members.

The exchange took place shortly after Trump arrived aboard Air Force One following the FIFA World Cup final in New Jersey. Reporters questioned the president about a war that has stretched to nearly five months after administration officials initially characterized the operation as one expected to last only several weeks. Trump rejected the premise that the conflict had exceeded its original scope, arguing instead that the mission had evolved.

"This is a far bigger job that we're doing," Trump said. "We were doing a little job, stopping them from having a certain capability. Now, we're just ending it."

The president maintained that the military objectives had changed from preventing Iran from achieving what he described as a critical capability to permanently eliminating its ability to develop a nuclear missile.

"It's really not the same thing," Trump said, adding that the United States is now "ending any chance where they could have a nuclear missile."

As he attempted to explain when key objectives had been achieved, Trump appeared to pause and restart his answer.

"If you look at it, after a week-and-a-half... not four weeks, a week-and-a-half, two weeks," he said. "We stopped them from probably, but I don't want to have the word 'probably'..."

Trump did not complete the sentence. Instead, he looked toward reporters and concluded the exchange by saying, "Thank you very much," before turning and walking toward Marine One without taking additional questions.

The president had also been asked about the deaths of three U.S. service members over the weekend during exchanges with Iranian-backed forces. According to U.S. officials, the latest casualties brought the reported American death toll in the conflict to 17, while hundreds of additional service members have been wounded since hostilities began.

"We feel very badly," Trump said of the deaths. He then defended the broader military campaign, stating, "But those people, those great patriots, are out there fighting [so] that Iran cannot have a nuclear weapon. Iran has been very, very badly damaged. They've lost everything, almost, militarily."

Trump did not provide evidence supporting his assessment of Iran's military capabilities. At the same time, the latest attacks that killed U.S. troops indicate Iran and its allied forces continue to retain the capacity to conduct military operations. No independent assessment released by the Pentagon was cited during the exchange to substantiate Trump's characterization that Iran has "lost everything, almost, militarily."