The top U.S. military commander for the Middle East vowed Wednesday to take “appropriate action” if an investigation finds that senior defense officials altered intelligence reports on the Islamic State and other militant groups in Syria to exaggerate progress being made against the terrorist groups.

A Defense Department inspector general began an investigation after an intelligence officer at the Central Command lodged a complaint in July. In his first remarks about the allegations, Gen. Lloyd Austin, commander of the U.S. Central Command, told the Senate Armed Services Committee that he welcomed the Defense Department inspector general’s investigation. But he said he could not comment directly until the review was over.

“I assure you that we will do everything in our power to make sure that the whistleblowers remain protected and that there is no retaliation. This is absolutely important,” Austin said.

Committee members expressed concern.

“Published media reports suggest that the CIA’s estimate of ISIL’s manpower has remained constant, despite U.S. airstrikes-which suggests that either they were wrong to begin with, or that ISIL is replacing its losses in real time. Neither is good,” said committee chairman Sen. John McCain, R-Ariz.

“Indeed, this committee is disturbed by recent whistleblower allegations that officials at Central Command skewed intelligence assessments to paint an overly-positive picture of conditions on the ground,” McCain said.

He said the committee was investigating the allegations.

“If true, those responsible must be held accountable,” he said.

The Daily Beast says several dozen intelligence analysts at Central Command, which oversees the war effort, have formally complained that their reports on IS and the al-Qaida’s branch in Syria were being inappropriately altered by senior officials.

Rhode Island Sen. Jack Reed, the ranking Democrat on the committee, said it’s important to wait for the Defense Department’s inspector general to be finished before making any judgment.

“I have no doubt you take such allegations as seriously as we in Congress do,” Reed said. “Like Sen. McCain, I expect the committee will be kept apprised of this investigation as it continues.”

In his opening statement, Austin updated the committee on conditions in Iraq and Syria. Austin said the Iraqis must recruit and retain new forces or gains will be limited against the Islamic State.

(AP)