Defense Secretary Ash Carter convened an extraordinary war council Monday on Iraq’s doorstep six days after taking office, gathering military and diplomatic leaders to discuss the Obama administration’s oft-criticized strategy for countering the Islamic State group.

He left suggesting the approach is mostly on track.

“The discussion indicated clearly to me that this group (the Islamic State) is hardly invincible,” Carter told reporters after six hours of closed-door talks with the officials he dubbed “Team America.”

He gave no indication that he that he thinks the strategy needs an overhaul.

“Our discussion this afternoon affirmed the seriousness and the complexity of the threat posed by ISIL, especially in an interconnected and networked world,” he said, using an alternate acronym for the militants. “Lasting defeat of this brutal group can and will be accomplished.”

Carter said the U.S.-led aerial bombing campaign in Iraq is going well, and he expressed confidence that the U.S. military is well suited to carrying out a longer-term effort to train and equip an opposition rebel force in Syria. He specified two areas for needed improvement in the overall strategy: more creative use of social media to counter the Islamic State’s messaging campaign and getting more out of some coalition member countries, though he did not specify which ones.

Carter is returning to Washington today to report to President Barack Obama.

Also Monday, Lt. Gen. James L. Terry, who is commanding the war effort in Iraq and Syria, told reporters that the Islamic State fighters are “halted, on the defensive” in Iraq and facing a new counterattack by Iraqi forces in Anbar province to retake a town the militants seized earlier this month. Terry said he is confident the Iraqi push, dubbed “Lion’s Revenge,” will succeed in retaking the town of al-Baghdadi.

But Terry said of the Islamic State group, “No doubt, they’re adaptive.”

Carter said he assembled U.S. generals, diplomats and intelligence officials in Kuwait not just to hear the latest on battlefield progress but also to better understand the intellectual underpinnings of Obama’s strategy, including the ways military force is supposed to combine with political and economic measures to reverse the Islamic State’s gains and eventually defeat it.

“It is a problem that has an important military dimension, but it’s not a purely military problem — it’s a politico-military problem,” he said.

The gathering was a highly unusual way for a Pentagon chief to begin his tenure. Aides said participants were told in advance to leave their usual talking points home and be prepared for a freewheeling discussion.

In remarks to troops at Camp Arifjan before the conference began, Carter said the key to success against the Islamic State is ensuring that the countries threatened by the group can preserve the gains achieved by the U.S.-led military campaign.

“We will deliver lasting defeat, make no doubt,” Carter said, adding, “It needs to be a lasting defeat.”

The meeting was convened against the backdrop of heavy criticism, mostly by Republicans, of Obama’s strategy for countering Islamic extremism.