Story highlights Elizabeth Shackelford was an award-winning foreign service officer

She warns of the administration's emphasis on the military

Washington (CNN) A rising star at the State Department has written a blistering resignation letter to Secretary of State Rex Tillerson, saying that under his leadership, the agency's influence has withered and morale among staff has plummeted, in part because of the "stinging disrespect" shown by the Trump administration.

In the letter, obtained by CNN and first reported on by Foreign Policy , Elizabeth Shackelford wrote on November 7 that if Tillerson is unable to show the leadership required to lead the agency and reverse an exodus of diplomats like her, "I would humbly request that you follow me out the door."

Shackelford, who served in South Sudan, Kenya and Poland, wrote that under Tillerson, the State Department is being "diminished" and its influence around the world undercut as the administration increasingly relies on the military at a time of perilous foreign policy challenges.

"We have ceded to the Pentagon our authority to drive US foreign policy," Shackelford wrote, "at the behest of the White House, but to our detriment as a nation."

Withering bipartisan criticism

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