The former deputy and acting director of the Central Intelligence Agency is resigning as a non-resident senior fellow from Harvard’s Kennedy School after Chelsea Manning was invited to be a visiting fellow this year.

In his resignation letter on Thursday, Michael J. Morell said he “cannot be part of an organization” that “honors a convicted felon and leaker of classified information.”

“Ms. Manning was found guilty of 17 serious crimes, including six counts of espionage, for leaking hundreds of thousands of classified documents to Wikileaks, an entity that CIA Director Mike Pompeo says operates like an adversarial foreign intelligence service,” Mr. Morell wrote. “Senior leaders in the military have stated publicly that the leaks by Ms. Manning put the lives of US soldiers at risk.”

The Kennedy School’s invitation will “assist Ms. Manning in her long-standing effort to legitimize the criminal path that she took to prominence,” the letter continued, and “may encourage others to leak classified information as well.”

Mr. Morell emphasized that he fully supports “Ms. Manning’s rights as a transgender American, including the right to serve our country in the US military.”

“But, it is my right, indeed my duty, to argue that the School’s decision is wholly inappropriate and to protest it by resigning from the Kennedy School – in order to make the fundamental point that leaking classified information is disgraceful and damaging to our nation,” he wrote.

The Institute of Politics at the Harvard Kennedy School announced on Wednesday a group of visiting fellows that includes Ms. Manning, former White House press secretary Sean Spicer and former Hillary Clinton campaign manager Robby Mook.

Mr. Morell was a non-resident senior fellow at the school’s Belfer Center for Science and International Affairs.

Ms. Manning’s invitation to Harvard was widely panned on the right, including by Kennedy School alumnus Bill Kristol.