A visiting professor at Middlebury College accused the U.S. ambassador of Denmark of banning him from an event because of his criticism of President Trump.

Professor Stanley Sloan, who is a former CIA officer and a nonresident senior fellow for the Atlantic Council, was slated to deliver a keynote address before the Danish Atlantic Council during an event honoring NATO that was co-sponsored by the U.S. Embassy in Copenhagen. In a tweet posted Saturday, Sloan said his address had been canceled because of his criticisms of Trump.

“Cancel that! I've just received word from the Danish Atlantic Council that the US Embassy in Copenhagen, a cosponsor of the meeting, has vetoed my participation due to my critical evaluation of Trump's impact on transatlantic relations,” Sloan tweeted. “Stunned and concerned about our country.”

Cancel that! I've just received word from the Danish Atlantic Council that the US Embassy in Copenhagen, a cosponsor of the meeting, has vetoed my participation due to my critical evaluation of Trump's impact on transatlantic relations. Stunned and concerned about our country. — Stanley R. Sloan - Defense of the West (@srs2_) December 7, 2019

Lars Bangert Struwe, the head of the Danish Atlantic Council, placed the blame on Ambassador Carla Sands, telling Sloan, “The Danish Atlantic Council via the official channels became instructed that Ambassador Carla Sands does not want presence at the Conference.”

He reiterated his sentiment in a statement to Buzzfeed, “The US embassy demanded that he be removed as a speaker.”

Sands, who was a major donor to Trump, was a controversial ambassador nominee and has been criticized for posting pro-Trump materials on her personal Twitter account.

In a series of tweets posted Sunday morning, the U.S. Embassy in Copenhagen announced that it was canceling the event following the controversy of Sloan’s exclusion.

“In our planning for the Seminar as co-hosts and co-sponsors, the U.S. Embassy and [the Atlantic Council] had jointly agreed on a program of speakers with a wide range of views on the Alliance,” they tweeted. “Mr. Stanley Sloan’s proposed last-minute inclusion in the program by [the council] did not follow the same deliberative process of joint decision-making and agreement that we followed when recruiting all other speakers.”

Mr. Stanley Sloan’s proposed last-minute inclusion in the program by @AtlantDK did not follow the same deliberative process of joint decision-making and agreement that we followed when recruiting all other speakers. — U.S. Embassy Denmark (@usembdenmark) December 8, 2019

Sloan had been invited to speak at the event 10 days before the planned conference.

He told Buzzfeed, “I've criticized Republican and Democratic administrations. I always admired the State Department for sponsoring people like me who went out and told what they thought was the truth and the facts and didn't pull their punches. I bragged to American and European audiences about how this shows the strength of our democracy. But it also now shows how our democracy is threatened.”

Sands, 59, was an investor prior to landing her role as a U.S. diplomat. Prior to her career in investing, she was an actress and chiropractor. She starred in two films, including Wild Zone and Deathstalker and the Warriors from Hell.