A week after President Obama vowed not to get "dragged into another ground war in Iraq," his top military leader opened the door to just that. 

Joint Chiefs of Staff Chairman Gen. Martin Dempsey addressed the possibility of U.S. ground forces getting involved in the fight against the Islamic State during blunt testimony before the Senate Armed Services Committee on Tuesday. He said he would consider recommending that option if the international coalition being formed proves ineffective. 

"My view at this point is that this coalition is the appropriate way forward," Dempsey said. "I believe that will prove true, but if it fails to be true and if there are threats to the United States, then I of course would go back to the president and make a recommendation that may include the use of U.S. military ground forces." 

The comment is a departure from what Obama vowed in his address to the nation a week ago, and from what the president's top spokesman said just one day before Dempsey's testimony. And it marks the latest mixed message to emerge from the administration on the fight against ISIS, which for weeks U.S. military advisers have described in more urgent and dire terms than others in the administration. 

Just hours after Dempsey's testimony, a spokesman released a statement attempting to clarify his remarks. "The chairman doesn't believe there is a military requirement for our advisors to accompany Iraqi forces into combat," said Col. Ed Thomas

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He added, "the context of this discussion was focused on how our forces advise the Iraqis and was not a discussion of employing U.S. ground combat units in Iraq."

On Monday, White House Press Secretary Josh Earnest said: "I can say definitively that the president has ruled out sending American boots on the ground to be engaged in a combat role in Iraq and in Syria." 

He was echoing the president's pledge in his address last Wednesday that the expanding campaign "will not involve American combat troops fighting on foreign soil." 

Earnest, asked Tuesday about Dempsey's latest comments, stressed that the Joint Chiefs chairman was referring to a "hypothetical scenario." But he said Obama has been clear that he does not believe it would be in the country's security interests to deploy ground combat troops. 

Dempsey said Tuesday that ground troops are not needed at the moment but made clear he could change his recommendation if he found circumstances "evolving" in the region. He said he would recommend advisers accompany Iraqi troops on attacks against Islamic State targets if he comes to believe that's the right course. 

Dempsey provided one example of a scenario where he might recommend U.S. ground forces, saying they could be used to help Kurdish and Iraqi forces retake Mosul, now controlled by the Islamic State, or ISIS, by accompanying them or providing close-combat advice. 

The statement comes as the administration faces a deep divide in Congress that muddies traditional partisan lines over the possibility of ground forces being introduced. Many Democrats and Republicans oppose U.S. combat troops entering the fight. But some Republican lawmakers have criticized the president for appearing to rule out that option. 

"ISIS is an army," Sen. James Inhofe, R-Okla., top Republican on the committee, said Tuesday. "It will take an army to beat an army." 

Inhofe also criticized the administration for its "indecision and hand-wringing" before last week -- when Obama announced expanded airstrikes in Iraq and authorized airstrikes in Syria -- and expressed concern that the administration is still treating the mission as a chiefly counterterrorism mission. 

Dempsey and Defense Secretary Chuck Hagel, though, defended the U.S. strategy in Iraq and Syria. And, for those uneasy about the U.S. entering yet another conflict in the Middle East, they claimed the group will directly threaten the U.S. homeland if left unchecked. 

"It considers itself the rightful inheritor of Usama bin Laden's legacy," Hagel said. 

The testimony was interrupted several times by anti-war protesters, who appeared to be from the group Code Pink and shouted "no more war" before being led out of the room. 

The military leaders stressed the differences between this campaign and the last Iraq war. 

"This won't look like a 'shock and awe' campaign because that's simply not how ISIL is organized, but it will be a persistent and sustainable campaign," Dempsey said. 

In a lengthy opening statement, Hagel said ISIS has gained strength by exploiting Syria's civil war and sectarian strife in Iraq. 

"As it has seized territory across both countries and acquired significant resources and advanced weapons, ISIL has employed a violent combination of terrorist, insurgent, and conventional military tactics," he said.