WASHINGTON - US President Donald Trump said Tuesday that the US military will leave Iran in two or three weeks.

"We leave because there's no reason for us to do this," Trump told reporters at the White House.

"All I have to do is leave Iran, and we'll be doing that very soon, and they'll become tumbling down," Trump said when asked about his plan for lowering gas prices. The US national average gasoline price rose above 4 US dollars per gallon on Tuesday for the first time in more than three years, according to the American Automobile Association.

The US president, facing mounting pressure from energy market volatility and investor concerns over a prolonged conflict, has issued a number of conflicting remarks on the timeline of the war since the US and Israel launched massive attacks on Iran on Feb 28.

Trump said the US and Iran are negotiating, and it's possible that the war will come to an end sooner if the two countries reach a deal.

"It's possible that we'll have a deal because they want to make a deal. They want to make a deal more than I want to make a deal. But in a fairly short period of time, we'll be finished," Trump said.

"Now we have a group of people that's very -- that are very different. They're much more reasonable," Trump added.

Trump reiterated that it will be up to other countries to reopen the Strait of Hormuz and secure the crucial global energy waterway.

"If France or some other country wants to get oil or gas, you go up through the strait and -- the Hormuz Strait -- they'll go right up there and they'll be able to fend for themselves," Trump said.

In phone interviews with US media outlets on Tuesday, Trump said the US-Israeli war with Iran is likely to end soon.

"We won't have to be there much longer -- but we have more work to do in terms of killing their offensive, whatever offensive capability they have left," Trump told the New York Post.

He also told CBS News on Tuesday that the war against Iran "won't be long," while insisting that US military operations "are two weeks ahead of schedule." He had initially said the war would last four to six weeks after it began on Feb 28. It is now entering its fifth week.

On Tuesday morning, US Defense Secretary Pete Hegseth said that the coming days of the US-Israeli war with Iran "will be decisive," admitting that Iran retains the ability to retaliate.

Brad Cooper, chief of US Central Command, said in an update on Tuesday that there are 50,000 US troops deployed in the Middle East.