President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE has moved to fill the top job at the State Department office charged with dealing with the North Korean nuclear threat.

The White House announced Tuesday that Trump has nominated Susan Thornton, a career foreign service officer, to be assistant secretary of State for East Asian and Pacific affairs, a key position that has lacked an appointee for much of Trump's first year in office.

Thornton has served as the head of the bureau in an acting role since March, when the previous assistant secretary, Daniel Russell, an appointee of former President Obama, left the job.

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The State Department's Bureau of East Asian and Pacific Affairs is charged with overseeing an expansive portfolio that includes U.S. foreign policy in countries like China, Japan and Australia, as well as on the Korean Peninsula.

Thornton, a 26-year veteran of the State Department, was tapped to serve as the bureau's principal deputy assistant secretary in 2016.

Earlier this year, former White House chief strategist Stephen Bannon told The American Prospect that he wanted to remove Thornton from the department and install officials more hawkish on East Asian policy.

North Korea has stepped up the pace of its weapons tests this year, showing off significant developments in its ballistic missile and nuclear program. In September, the country detonated what it said was a hydrogen bomb — its most powerful nuclear weapon to date.

Trump has held that military options for dealing with North Korea are on the table, and has repeatedly threatened attacks on the isolated East Asian nation throughout his first year in office.

Secretary of State Rex Tillerson Rex Wayne TillersonGary Cohn: 'I haven't made up my mind' on vote for president in November Kushner says 'Alice in Wonderland' describes Trump presidency: Woodward book Conspicuous by their absence from the Republican Convention MORE has taken a more diplomatic approach to dealing with Pyongyang.

The Trump administration has faced criticism for delays in filling key leadership posts at the State Department, including ambassador to South Korea, a post that has been vacant since he took office. Critics have also accused the administration of driving out top talent among the agency's career ranks.