When it comes to U.S. military involvement in Iraq, "mission creep" is the wrong phrase to use, chairman of the Joint Chiefs of Staff Gen. Martin Dempsey said today, noting it should instead be "mission match."

That's because the U.S. military assessment teams currently working in Iraq will determine what capabilities Iraq's security forces will need from the United States. But one thing he seems certain of is that any future U.S. military role in Iraq will not require "an industrial strength" force.

"We will match the resources we apply with the authorities and responsibilities that go with them based on the mission we undertake, and that is to be determined," Dempsey said at a Pentagon briefing today.

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Dempsey outlined the teams' initial assessment that Iraqi security forces are "stiffening" their resistance to ISIS militants and are capable of defending Baghdad. However, taking the offensive might pose a logistical challenge for Iraq's military and Dempsey said the presence of Shiite volunteers assisting them has complicated the situation.

The U.S. troops protecting the embassy and parts of the airport are there to "preserve options" so the assessment teams can "develop options," Dempsey said.

Defense Secretary Chuck Hagel stressed that "none of these troops are performing combat missions. None will perform combat missions. President Obama has been very clear that American combat troops are not going to be fighting in Iraq again."

Dempsey predicted that if Iraq does go on the offensive to recapture territory captured by ISIS, they probably won't be able to do so by themselves. But he cautioned that "doesn't mean we would have to provide kinetic support. I'm not suggesting that that's the direction this is headed."

He stressed that "the first step in developing that campaign is to determine whether we have a reliable Iraqi partner that is committed to growing their country into something that all Iraqis will be willing to participate in. If the answer to that is no then the future's pretty bleak."

The nation's top military officer said the return of U.S. military forces in Iraq will not be a repeat of the previous U.S. military intervention in Iraq.

"This is not 2003. It's not 2006, " said Dempsey. "This is a very different approach than we've taken in the past. I mean, assessing, advising and enabling are very different roads than attacking, defeating and disrupting."

A different course of action will depend on whether ISIS is deemed to be a national security threat and poses a threat to the homeland or if the president "with our advice, decides that we have to take direction action. I'm just suggesting to you we're not there yet," Dempsey said.

The U.S. presence in Iraq isn't open-ended, he added, but he put it in the context of the long-term anti-Western ideology at play in the Middle East and it should not be just the U.S. taking it on alone.

"What we owe the President of the United States over time, in consultation with the Congress and an explanation to the people of the United States, is how we can deal with this long-term threat without having to repeat what we did in 2003 and 2006," Dempsey said.

The U.S. will continue to work on the possibility of airstrikes, he said, but that will all depend on the determinations made by the assessment teams. He said there's a better intelligence picture now than there was two weeks ago, but the intermingling of ISIS fighters and supporters makes it "a tough challenge to separate them, if we were to take a decision to strike."

For Dempsey, the first priority is making sure that there's a way to politically separate Sunni supporters from ISIS.

Hagel said that the assessments made on the ground will help the U.S. advise Iraq of "what we think they need to do and the different dynamics that are presented there, on the ground, and how they can best use their forces, as we continue to advise them."

He also announced that a second Joint Operations Center has been established in the northern Iraqi city of Erbil. The arrival of 20 personnel to open that center means there are now 200 advisers in Iraq, and that number will grow as more personnel are added to that Joint Operations Center. Overall there are now about 770 U.S. military personnel in Iraq once the additional forces sent for security are factored in.