More departures expected at nation's top intelligence office

Grenell has said he is only temporarily filling the position of acting director of American spy agencies, but he is already making his mark. Grenell, a President Donald Trump loyalist, is also still serving as the US ambassador to Germany. After his appointment to the intelligence post this week, officials at the office of the director of national intelligence (ODNI) made calls to US diplomats in Germany inquiring about Grenell's leadership style, two sources familiar with the matter told CNN.

Earlier this week, Grenell quickly forced out the number two intelligence official in the US government, Andrew Hallman, a source with knowledge of the situation confirmed to CNN. Hallman was an intelligence veteran and well respected in the intelligence community.

CNN reported earlier this week that Hallman was leaving. The New York Times first reported Grenell ousted him.

There are fears within the intelligence community that Hallman may not be the only top official forced out. Career intelligence professionals worry that Shelby Pierson, the person in charge of evaluating intelligence regarding election security with the ODNI, will also be fired, according to a former top intelligence official.

Pierson is still on the job, according to sources with knowledge of her status. She did not reply to a request for comment.

She led the recent briefing to the House Intelligence Committee in which the intelligence assessment regarding Russia trying to interfere in this year's election to help Trump was revealed.

Trump said Friday he was eyeing four people as possibilities to officially nominate for the job to lead the intelligence office.