Brian Hook, the U.S. special representative for Iran, is leaving his post, the State Department announced Thursday, just as the Trump administration is attempting to rally the international community to extend a soon-to-expire arms embargo on the regime in Tehran.

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

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"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," he said. "He has been a trusted adviser to me and a good friend. I thank him for his service."

Hook, who has been in the role for two years, will be replaced by current special representative for Venezuela Elliott Abrams -- a noted hawk on Iran who would be expected to continue, if not intensify, the administration’s aggressive posture toward Tehran.

Since he became envoy, Hook has been a key figure in the execution of the Trump administration’s “maximum pressure” campaign toward Iran that coincided with the U.S. withdrawal from the 2015 Joint Comprehensive Plan of Action (JCPoA) in 2018.

FILE - In this Nov. 29, 2018 file photo, Brian Hook, U.S. special representative for Iran, speaks at the Iranian Materiel Display at Joint Base Anacostia-Bolling in Washington.  (AP Photo/Carolyn Kaster, File)

FILE - In this Nov. 29, 2018 file photo, Brian Hook, U.S. special representative for Iran, speaks at the Iranian Materiel Display at Joint Base Anacostia-Bolling in Washington.  (AP Photo/Carolyn Kaster, File)

The administration has re-imposed sanctions to force Tehran to change its destabilizing activities in the region and elsewhere and has rallied other countries to do the same. At the beginning of the year, the U.S. took out the Islamic Republic Guard Corps Quds Force commander Qassem Soleimani in an airstrike.

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Hook’s departure comes just as the U.S. is ramping up pressure on the international community to extend a 13-year-old arms embargo on Iran that is due to expire in October.

The Trump administration intends to bring a resolution to the U.N. Security Council next week, but it is expected to be torpedoed by a veto by Russia and China even if it gathers the votes to pass. Should that fail, Pompeo has said the U.S. will use a clause in the U.N. resolution that enshrined the Iran deal that allows an individual nation to “snap back” sanctions on Iran.

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Hook, in a call with reporters earlier Thursday, had said it would be “diplomatic malpractice” for other countries to allow the embargo to expire and said there was "no question" it was the right thing to do.

"We have an objective to extend the arms embargo," he said. "That can be done the easy way or it can be done the hard way, but it’s going to be extended."

Fox News' Rich Edson contributed to this report.