Gen. Ray Odierno, the Army chief of staff, is the latest military official in recent days to push back against President Obama's promise to keep combat soldiers out of Iraq as the U.S. works with a multinational coalition to stamp out the Islamic State of Iraq and Syria (also known as ISIS, or ISIL).
"I don't rule anything out. I don't ever rule anything out, personally," Odierno said Friday when asked if the U.S. may eventually have to embed special operations forces on the front lines with Iraqi troops, the Washington Post reports.
There are currently 1,600 U.S. troops in Iraq, but they're not engaged in combat operations. Odierno said the 1,600 represented a "good start," but more may be needed in what's expected to be a years-long effort.
Mr. Obama has said repeatedly he won't be committing combat troops to the effort.
"I want to be clear: the American forces that have been deployed to Iraq do not and will not have a combat mission," Mr. Obama told troops at MacDill Air Force Base in Tampa, Florida on Wednesday.
Odierno is one of a handful of current and former military leaders who have called into question the president's promise.
Retired Gen. James Mattis told the House Intelligence Committee on Thursday that "you just don't take anything off the table up front, which it appears the administration has tried to do."
He added, "Specifically, if this threat to our nation is determined to be as significant as I believe it is, we may not wish to reassure our enemies in advance that they will not see American 'boots on the ground.' "
The Chairman of the Joint Chiefs of Staff, Army Gen. Martin Dempsey, similarly told the Senate Armed Services Committee Tuesday that he could recommend deploying combat forces, should the evolving fight call for it.
"If we reach the point where I believe our advisers should accompany Iraqi troops on attacks against specific ISIL targets, I will recommend that to the president," Dempsey said.
Former Defense Secretary Robert Gates said on "CBS This Morning" that "there will be boots on the ground if there's to be any hope of success in the strategy. And I think that by continuing to repeat that [the U.S. won't put boots on the ground], the president, in effect, traps himself."