Retired US Navy Adm. William McRaven, former head of US Special Operations Command, has delivered fierce criticisms of President Donald Trump in several opinion columns.

Here are a few of the criticisms McRaven has already leveled against Trump.

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Retired US Navy Adm. William McRaven, former head of US Special Operations Command, has delivered fierce criticisms of President Donald Trump in several opinion columns published in The New York Times and Washington Post.

McRaven's 36-year military career was marked by several high-profile accomplishments, including his leadership role in Operation Neptune Spear, targeting al-Qaida leader Osama bin Laden, in 2011.

He retired from the Navy in 2014 and became the chancellor of the University of Texas system in 2015. Two years later, he said he would leave that job, citing health concerns.

McRaven has written several bestselling books about leadership, including "Make Your Bed: Little Things That Can Change Your Life ... And Maybe the World" and "Sea Stories: My Life in Special Operations."

McRaven has taken issue with Trump's policies and demeanor throughout his presidency, writing several striking opinion columns and criticizing him in interviews. While it is not uncommon for retired military officers to speak for or against a sitting president, McRaven's comments have attracted significant attention due to his seniority and service.

Trump has responded by denigrating McRaven's military service and accusing him of being politically biased, calling the retired admiral a "Hillary Clinton fan" and an "Obama backer" during a Fox News interview in November.

"Wouldn't it have been nice if we got Osama bin Laden a lot sooner than that? Wouldn't it have been nice?" Trump said.

McRaven has said he "did not back Hillary Clinton or anyone else" during the 2016 presidential election and denied reports he was on the short list to be Clinton's vice presidential running mate.

Here are a few of McRaven's criticisms of Trump: