Derek Harvey, a top adviser on the Middle East to President Donald Trump, was fired from the National Security Council on Thursday.

Harvey's departure comes amid speculation about major shake-ups at the White House, the Weekly Standard reports. These shake-ups include possible conflicts between Trump and both Attorney General Jeff Sessions and Secretary of State Rex Tillerson.

Two sources told the Standard that Harvey's departure was not a direct product of staff fighting, but that several top administration members saw Harvey as too close to White House chief strategist Stephen Bannon.

Harvey was apparently a strong advocate of Trump's decision to bomb a Syrian airfield in April in retaliation for the regime of Syrian President Bashar al-Assad using chemical weapons on civilians days earlier. Harvey also supported a more bellicose Iran strategy than either Tillerson or Secretary of Defense James Mattis.

Mattis, in particular, had strong disagreements with Harvey. Sources told the Standard that Mattis raised his concerns with National Security Adviser H.R. McMaster, who was the one to fire Harvey on Thursday morning.

Harvey, a long-time intelligence professional with wide knowledge of the Middle East, played a critical role in the administration's Iran, Syria, and Iraq policies. He has extensive experience as an intelligence officer and analyst for the military, embassies, and the Defense Intelligence Agency.

He is also known for recognizing the growing threat of the Iraqi insurgency following the U.S. invasion in 2003, and as a key ally of retired Gen. David Petraeus in executing the surge in Iraq. Petraeus has called Harvey his "favorite intelligence officer."

"General McMaster greatly appreciates Derek Harvey's service to his country as a career Army officer, where he served his country bravely in the field and played a crucial role in the successful surge in Iraq, and also for his service on Capitol Hill and in the Trump administration," NSC spokesman Michael Anton said. "The administration is working with Colonel Harvey to identify positions in which his background and expertise can be best utilized."

Harvey may remain in government, and is being considered for both policy and intelligence roles.