Trump, facing a war-wary American public and sliding approval ratings, on Wednesday night said the US had destroyed Iran's navy and air force, and crippled its ballistic missile and nuclear programs.
He added that the US would continue to hit targets in the Islamic Republic over the next two to three weeks.
"Tonight, I'm pleased to say these core strategic objectives are nearing completion," he said.
"We are going to finish the job, and we're going to finish it very fast. We're getting very close." Trump and his advisers have offered shifting explanations and timelines for the conflict, now in its fifth week.
Some allies are pushing the president to assuage growing concerns among Americans, most of whom oppose the conflict and are upset at rising petrol prices due to disruptions in the global oil supply.
The president briefly addressed those concerns, saying that prices would come back down. He notably did not commit to any timeline to end the war, and said the US would begin hitting energy and oil targets if it was deemed appropriate, even as he said the end was near.
"Many Americans have been concerned to see the recent rise in gasoline prices here at home. This short-term increase has been entirely the result of the Iranian regime launching deranged terror attacks against commercial oil tankers of neighbouring countries that have nothing to do with the conflict," Trump said.
Trump did not directly discuss NATO, despite telling Reuters in an interview earlier in the day that he would also express his disgust with the alliance for what he considers its lack of support for US objectives in Iran.
