However, theRepublican leader played down the potential for military conflict in theregion, saying he believed Iran did not want a confrontation with the UnitedStates.
"We want tohave protection in the Middle East. We're going to be sending a relativelysmall number of troops, mostly protective," Trump said as he left theWhite House for a trip to Japan.
The Pentagon saidonly about 900 of the 1,500 troops will be newly deploying and that 600 arealready in the region and will be extended. It said they include Patriotmissile battery personnel, manning for surveillance aircraft and engineers.
"Right now, Idon't think Iran wants to fight. And I certainly don't think they want to fightwith us," Trump said.
"But theycannot have nuclear weapons," he continued. "They can't have nuclearweapons. And they understand that."
The U.S. militarydeployed a carrier strike group, bombers and Patriot missiles to the MiddleEast earlier this month in response to what Washington said were troublingindications of possible preparations for an attack by Iran.
Rhetoric betweenTehran and Washington has escalated in recent weeks as the United Statestightened sanctions with what it said was the goal of pushing Iran to makeconcessions beyond the terms of its 2015 nuclear deal.
Trump withdrew fromthe 2015 nuclear deal between Iran and six major powers a year ago and now isseeking to block all Iranian oil exports.
Washington believesa series of recent attacks in the region may have been inspired by Iran,including a rocket attack in Baghdad's heavily fortified Green Zone and whatSaudi Arabia described as armed drone attacks on two oil pumping stations andthe sabotage of four vessels including two Saudi oil tankers.
Trump warned onMonday that Iran would be met with "great force" if it attacked U.S.interests in the Middle East.