Numerous agencies produce intelligence assessments related to the Iraq war, including the Defense Intelligence Agency, the Central Intelligence Agency and others. Colonel Ryder said it was customary for them to make suggestions on one another’s drafts. But he said each agency had the final say on whether to incorporate those suggestions. “Further, the multisource nature of our assessment process purposely guards against any single report or opinion unduly influencing leaders and decision makers,” he said.

It is not clear how that review process changes when Defense Intelligence Agency analysts are assigned to work at Centcom — which has headquarters both in Tampa, Fla., and Qatar — as was the case of at least one of the analysts who have spoken to the inspector general. In the years since the Sept. 11, 2001, attacks, the Pentagon has relocated more Defense Intelligence Agency analysts from the agency’s Washington headquarters to military commands around the globe, so they can work more closely with the generals and admirals in charge of the military campaigns.

Mr. Obama last summer authorized a bombing campaign against the Islamic State, and approximately 3,400 American troops are currently in Iraq advising and training Iraqi forces. The White House has been reluctant, though, to recommit large numbers of ground troops to Iraq after announcing an “end” to the Iraq war in 2009.

The bombing campaign over the past year has had some success in allowing Iraqi forces to reclaim parts of the country formerly under the group’s control, but important cities like Mosul and Ramadi remain under Islamic State’s control. There has been very little progress in wresting the group’s hold over large parts of Syria, where the United States has done limited bombing.

Some senior American officials in recent weeks have provided largely positive public assessments about the progress of the military campaign against the Islamic State, a Sunni terrorist organization that began as an offshoot of Al Qaeda but has since severed ties and claimed governance of a huge stretch of land across Iraq and Syria. The group is also called ISIS or ISIL.

In late July, retired Gen. John Allen — who is Mr. Obama’s top envoy working with other nations to fight the Islamic State — told the Aspen Security Forum that the terror group’s momentum had been “checked strategically, operationally, and by and large, tactically.”