Washington DC - President Donald Trump's administration has removed Admiral Linda Fagan – the first woman to lead a US military service – as the head of the Coast Guard.

The Department of Homeland Security (DHS), which oversees the Coast Guard, did not immediately respond to a request on Tuesday for comment on Fagan's dismissal.

Fox News cited a senior official saying reasons included her failure to address border security threats, a supposed excessive focus on diversity, equity, and inclusion, and an "erosion of trust" over the Coast Guard's investigation into sexual assault cases.

Trump and other Republicans have long railed against government programs aimed at fostering diversity, and militarizing the border is a key priority for the president, who declared a national emergency at the US frontier with Mexico on the first day of his new term.

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"She served a long and illustrious career, and I thank her for her service to our nation," acting DHS secretary Benjamine Huffman said in a message to the Coast Guard, which is one of the five US military branches.

Fagan had led the Coast Guard since 2022, and previously held posts including vice commandant of the service.

She "served on all seven continents, from the snows of Ross Island, Antarctica to the heart of Africa, from Tokyo to Geneva, and in many ports along the way," according to an archived version of her biography, which is no longer available on the Coast Guard website.