Carolyn Kaster, Associated Press
White House press secretary Josh Earnest speaks during the daily news briefing at the White House in Washington, Wednesday, Aug. 26, 2015. Earnest discussed the on-air shooting in Moneta, Va., the 2016 Democratic nomination, and other topics.

WASHINGTON — The Pentagon's inspector general is investigating an allegation that the military command overseeing the anti-Islamic State campaign distorted or altered intelligence assessments to exaggerate progress against the militant group, a defense official said Wednesday.

The official was not authorized to discuss the probe publicly and so spoke on condition of anonymity.

The investigation was first disclosed by The New York Times. The paper reported that the investigation began after at least one civilian Defense Intelligence Agency analyst told authorities that he had evidence that officials at U.S. Central Command were improperly reworking conclusions of assessments prepared for policy makers, including President Barack Obama.

Details of the allegations were not available. A spokeswoman for the inspector general's office, Bridget Serchak, declined to comment.

Pentagon press secretary Peter Cook said he could not confirm the probe. The Pentagon typically does not publicly comment on the work of the inspector general's office, which is an independent arm of the Defense Department.

Cook said Defense Secretary Ash Carter "counts on independent intelligence and analysis from a variety of sources to help him make critical decisions about the nation's security."

White House press secretary Josh Earnest said Obama "places a premium" on getting unvarnished intelligence assessments and a range of views for policymakers.

"That yields, in the minds of our experts, the best, richest account of the facts on the ground," Earnest said, adding that the president is confident he is receiving honest intelligence assessments.

A Pentagon spokesman, Navy Capt. Jeff Davis, said Pentagon and Central Command officials have been publicly candid about the difficulty of the war against the Islamic State. At times, however, they have painted a rosier picture than was reflected by developments on the ground.

On May 15, for example, Brig. Gen. Thomas Weidley, who at the time was chief of staff to the military headquarters running the war, told reporters that the Islamic State was "losing and remains on the defensive." Even as he spoke, Iraqi officials were saying that IS fighters had captured the main government compound in Ramadi, the capital of Anbar province. Two days later the city fell, marking a significant victory for IS and a setback for the U.S. and Iraq.

Air Force Col. Patrick Ryder, a spokesman for Central Command, said he could not discuss ongoing investigations.

"The (inspector general) has a responsibility to investigate all allegations made and we welcome and support their independent oversight," Ryder said.

Ryder said the government's numerous intelligence agencies routinely produce a wide range of "subjective assessments related to the current security environment," and that it is customary for agencies to comment on others' draft assessments.

"However, it is ultimately up to the primary agency or organization whether or not they incorporate any recommended changes or additions. Further, the multi-source nature of our assessment process purposely guards against any single report or opinion unduly influencing leaders and decision-makers," Ryder said.

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Associated Press Writer Nancy Benac contributed to this report.