Secretary of State Mike Pompeo announced Thursday that U.S. Special Representative for Iran Brian Hook is resigning from his position. Hook, a political appointee, has served in the role since September 2018.

"Special Representative Hook has been my point person on Iran for over two years and he has achieved historic results countering the Iranian regime," Pompeo said in a statement.

"He successfully negotiated with the Iranians the release of Michael White and Xiyue Wang from prison. Special Representative Hook also served with distinction as the Director of Policy Planning and set into motion a range of new strategies that advanced the national security interests of the United States and our allies," Pompeo continued. "He has been a trusted advisor to me and a good friend. I thank him for his service."

Hook was a staunch supporter of Trump’s “maximum pressure” policy against Iran which intends to squeeze the Iranian economy with sanctions and other measures. He had also been in charge of an effort to extend an United Nations arms embargo against the Middle Eastern country.

Hook was previously the State Department’s Director of Policy Planning, where he received criticism for pushing out a career staffer in 2017 with ties to the Obama administration. Hook is now returning to the private sector after previously working as a corporate lawyer.

Hook will now be replaced in the special envoy position by Elliott Abrams, the current U.S. Special Representative for Venezuela. Abrams has served under the Reagan and George W. Bush administrations and holds neoconservative views on foreign policy.

Abrams was involved in the Iran-Contra affair and pleaded guilty to lying to Congress about his knowledge of the scheme. He was later pardoned by President George H.W. Bush.