Director of National Intelligence James Clapper is vehemently defending his role in assessing the Islamic State’s strength, telling a private listserv of intelligence professionals "whatever flaws I have, politicizing intelligence isn't one of them,"  according to an email obtained by Fox News.

The email was sent by Clapper Friday afternoon to a private listserv, and its title refers to a report by The Guardian newspaper, alleging that Clapper's contact with an intelligence officer at the US Central Command was "frequent and unusual." 

The Defense Department's Inspector General is investigating allegations from analysts at Centcom that the intelligence was manipulated to paint a more positive assessment of the military campaign against ISIS.

In the email, Clapper said the allegation has no merit. "Ackerman's Guardian article is fictional BS," he writes. Clapper said his contact with the head of US Central Command's intelligence branch, was "...once or twice a week, as a small part of my prep for Oval sessions with POTUS (President of the United States)."  The Guardian report did refer to the secure video teleconference. 

"It has been my standard practice in the five years in this job, as it has been for decades, to reach out to people directly, and not always depend on the formal 'chain of command' for input," Clapper writes.

A former senior intelligence official said The Guardian story had "clearly struck a nerve" with Clapper, questioning why the nation's intelligence chief would not have reached out to his own staffer at Centcom.  One of the major post 9/11 reforms was the standing up of the Office of the Director of National Intelligence or ODNI,  and the placement of staff in the combatant commands, of which Centcom is one.

Clapper's spokesman confirmed the authenticity of the 9/11/15 email, adding the ODNI was also in frequent contact with his staffer on the ground. The discussions are "strictly limited to tactical developments such as what happened on the ground overnight," ODNI spokesman Brian Hale said. "They are not broad or strategic assessments."

Hale added, "The intelligence community has a well-earned reputation for analytic objectivity and our assessments are not always in full agreement with Centcom and other commands around the world. These competing views are valuable to senior policy makers and are indeed expected."

The Director of the Defense Intelligence Agency, Lt. Gen. Vincent Stewart said at an intelligence conference Thursday hosted by INSA (Intelligence and National Security Alliance) and AFCEA (The Armed Forces Communications and Electronics Association) that "We will be better as a result of a very open investigation."   Stewart said "the investigation will play itself out" and help "figure out if we did something wrong." 

Two sources, one intelligence, the other military, said the number of intelligence analysts who had logged complaints was much closer to a half dozen, not the 50 cited in print reports last week.

Fox News contacted reporter Spencer Ackerman at The Guardian for comment.  Spencer said he stands by the original story.

Catherine Herridge is an award-winning Chief Intelligence correspondent for FOX News Channel (FNC) based in Washington, D.C. She covers intelligence, the Justice Department and the Department of Homeland Security. Herridge joined FNC in 1996 as a London-based correspondent.