Retired General James Mattis, former commander of the U.S. Central Command, told Congress Thursday that he disagrees with President Barack Obama's public objection to committing ground troops in the fight against the Islamic State.
In an open hearing of the House Intelligence Committee, Mattis said he agrees with Republican critics of Obama that the U.S. should not be so specific in spelling out what steps the U.S. won't take to win that fight.
"Once you go into it, you don't tell your adversary in advance what you're not going to do," Mattis told the committee.
"We have the most skillful, the fiercest and certainly the most ethical ground forces in the world," he said. "And I don't think we should reassure the enemy in advance that they'll never face them."
Aside from tipping off the Islamic State, Mattis said that saying publicly the U.S. will never commit ground troops to the operation will likely make it harder for the U.S. to get the most from its allies.
"The fewer restrictions we place on our own selves going into this, the more apt we are to see other nations give their full measure," he said.
"If we put any restrictions in terms of how much time we're willing to commit to it, or if we say there's certain elements of our national power that we're going to take off the table in advance, it can perhaps work against us in terms of building the coalition that'll give full support," Mattis added.
Republicans have been criticizing Obama's plan over the last few days, just as the White House has been seeking congressional support for its plan to provide aid and training to moderate Syrian rebels who are fighting the Islamic State. The House approved that authorization on Wednesday, and the Senate was expected to approve it Thursday.
But that authorization doesn't deal with whether Obama has the authority to increase airstrikes against the terrorist group in both Syria and Iraq. Several members of the House and Senate, including some Democrats, have said Congress needs to approve new authority before officials can pursue that strategy in the long-term.
One of the reasons some want Congress is to approve new authority is that administration officials have said it would take years to fight the Islamic State. At the Intelligence hearing Thursday, Mattis agreed.
"It's going to be an era of skirmishing over many years," Mattis said. "It's going to be a time somewhat akin to the U.S. cavalry versus the American Indian 1850 to 1905. It's not going to be over in one year, two years. This is a long-term fight."