Facing a war-wary American public, sliding approval ratings and pressure from some allies to outline his war aims in more precise and consistent terms, Trump 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, and assured viewers that the US would finish the job "very fast".
But he glossed over some unresolved issues that remain during his 19-minute speech, such as the status of Iran's enriched uranium and access through the Strait of Hormuz, a conduit for global oil supplies which Iran has effectively closed since the US and Israel launched the war on February 28.
And he notably suggested the war could escalate if Iranian leaders did not capitulate to US terms during negotiations, with strikes on Iran's energy and oil infrastructure possible.
He asked Americans to keep perspective about a war now in its fifth week, pointing out that the conflict was much shorter than the country's involvement in several previous wars.
"I can say tonight that we are on track to complete all of America's military objectives shortly, very shortly. We're going to hit them extremely hard over the next two to three weeks. We're going to bring them back to the stone ages where they belong," Trump said.
"In the meantime, discussions are ongoing ... The new group is less radical and much more reasonable. Yet if during this period of time, no deal is made, we have our eyes on key targets."
Trump and his advisers have offered shifting explanations and timelines for the conflict. 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, mainly to say that petrol prices would soon go down, that it was a worthwhile short-term sacrifice and that it was mainly Iran's fault.
"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.
Reflecting widespread sentiment that Trump's comments did not portend a short-term off-ramp, stocks fell, the dollar firmed and oil rose shortly after Trump's comments.
Earlier, Iranian President Masoud Pezeshkian said in a letter addressed to the people of the US that his country harbours no enmity towards ordinary Americans, Press TV reported.
Global oil supplies were expected to be hit twice as hard this month as in March, the International Energy Agency said on Wednesday, underlining the urgent need for an end to the conflict Trump began with Israel on February 28.
Two security sources from Pakistan, which is mediating in the conflict, earlier told Reuters that Pakistani officials had proposed a temporary ceasefire to both sides but had not heard back from either.
The conflict has killed thousands of people, spread across the region and caused unprecedented energy disruption.