A conference celebrating the 70th anniversary of NATO was canceled after the U.S. ambassador to Denmark, Carla Sands, objected to a speaker who has made statements critical of President Donald Trump, the Danish think tank co-sponsoring the event announced Sunday. 

Stanley Sloan, a former CIA analyst and author of "Defense of the West," had planned to deliver an address on the challenges facing the transatlantic alliance, and the West in general, at the conference, which was scheduled to take place Tuesday at the U.S. Embassy in Copenhagen. 

A day before Sloan left for Denmark, he said he was informed by the Danish Atlantic Council that the U.S. Embassy "vetoed my participation due to my critical evaluation of Trump's impact on transatlantic relations." 

"Stunned and concerned about my country," Sloan said in a tweet

The next day, the Danish Atlantic Council announced the conference had been canceled altogether. 

U.S. Ambassador to Denmark Carla Sands arrives for the New Year reception for the diplomacy at Christiansborg Castle, Denmark, Jan. 3, 2019.

"We have all the time known that Mr. Sloan has a critical approach towards President Donald Trump. That is no secret – especially when following his Twitter and Facebook profile," the Danish Atlantic Council Secretary-General Lars Bangert Struwe said in a statement

But Struwe said they "never doubted" that Sloan "would deliver an unpolitical and objective lecture," as he promised he would. 

When Sands objected to Sloan's appearance, Struwe said the council decided to pull the plug on the event because "the process has become too problematic." 

In a series of tweets, the U.S. Embassy said it "supports freedom of speech as enshrined in the First Amendment" and that it was "unfortunate" the Danish Atlantic Council decided to cancel the conference. 

"This event would have provided speakers and attendees an important opportunity to exchange views on security cooperation and strengthening #NATO for the future," the U.S. Embassy said. 

The American officials objected to Sloan's "proposed last-minute inclusion in the program," which "did not follow the same deliberative process of joint decision-making and agreement that we followed when recruiting all other speakers." 

But Struwe disputed that explanation and told The Washington Post that the U.S. Embassy, which was paying for the event, had not given any input on the other speakers. 

"I'm sorry that you objected to my inclusion in the conference," Sloan tweeted in reply to the embassy. "I am an experienced public diplomacy lecturer who always represents his country well."

"I have given presentations during Republican and Democratic administrations that criticized to one degree or another administration policy," he said. "I have always praised the State Department for its willingness to display our freedoms to foreign audiences. I hope we can return to that." 

Sloan posted the text of the address he had planned to give online. In the speech, he commends Sands for her "expression of support for the values on which the alliance is based as well as its strategic importance for both Demark and the United States." 

And he planned to say the "current crisis" facing NATO "did not start with Donald Trump, even though he certainly has brought it to a head." 

Sands is an entrepreneur, former chiropractor and former actress who appeared in the soap opera "The Bold and the Beautiful." She was appointed ambassador to Denmark by Trump and was approved by the Senate in November 2017.