President Barack Obama has reaffirmed that he does not intend to send US troops into combat against the Islamic State group, despite doubts about the ability of Iraqi forces, Kurdish fighters and Syrian rebels to carry out the ground fight on their own.
"The American forces do not and will not have a combat mission," Mr Obama told troops at MacDill Air Force Base in Florida.
It was a firm response to suggestions raised yesterday by his top military commander that under certain circumstances, American ground forces may be needed.
Mr Obama said US troops "will support Iraqi forces on the ground as they fight for their own country against these terrorists".
But, he added: "As your commander in chief, I will not commit you and the rest of our armed forces to fighting another ground war in Iraq."
Mr Obama offered a vision of a potent force that can have a major role in conflicts, a more forceful view than he has embraced before. But he still stressed that for the effort to succeed against the Islamic State group, the US will need to lead the international coalition and local forces must handle a significant role.
"Frankly, there just aren't a lot of other folks who can perform in the same way. In fact, there are none. There are some things only we can do. There are some capabilities only we have," he said.
"Our armed forces are unparalleled and unique. So when we've got a big problem somewhere around the world, it falls on our shoulders. Sometimes that's tough. But that's what sets us apart. That's why we're American."
Mr Obama spoke after consulting with officers at US Central Command, which oversees American military efforts in the Middle East.
His speech to troops at MacDill Air Force Base was one more chance to try to make the case for the air strike campaign against the militant group.
"We're going to degrade and ultimately destroy ISIL through a sustained counter-terrorism strategy," he said, using an acronym for the Islamic State organisation. "We mean what we say. Our reach is long. If you threaten America you will find no safe haven, we will find you eventually."
His meeting Gen Lloyd Austin, the Central Command head, and other officers took place as Congress prepared to vote on Mr Obama's request for authority to equip and train Syrian opposition fighters.
Politicians in both parties have raised worries that the US might be unable to find enough Syrian rebels who could be trusted to confront the Islamic State group or that their numbers would be sufficient.
Army Gen Martin Dempsey, the chairman of the Joint Chiefs of Staff, told a small group of reporters travelling with him to Paris that about half of Iraq's army is incapable of being an effective partner with the US to push the Islamic State group back in western and northern Iraq. He said the other half needs to be partially rebuilt with US training and additional equipment.
Gen Dempsey told senators yesterday that if it became necessary for US military advisers to accompany Iraqi troops into combat, he might "go back to the president and make a recommendation that may include the use of ground forces".