President Donald Trump’s nominee for ambassador to Iceland has apologized after a joke he made about the country becoming the U.S.’s 52nd state drew backlash amid rising tensions over Trump’s threats to annex Greenland.

“There was nothing serious about that,” Billy Long, a former Missouri Republican congressman who briefly served as commissioner of the Internal Revenue Service under Trump last year, told Arctic Today. “I was with some people, who I hadn’t met for three years, and they were kidding about Jeff Landry being governor of Greenland and they started joking about me and if anyone took offense to it, then I apologize.” Landry is the U.S. envoy to Greenland.

Long faced criticism and calls for his nomination to be rejected from Icelanders after Politico reported that he had joked Iceland would become the 52nd state and he would be made governor while speaking with lawmakers on the House floor Tuesday night.

A petition calling on Iceland Foreign Minister Katrín Gunnarsdóttir to reject Long’s nomination currently has nearly 4,000 signatures. 

“These words of Billy Long, who Donald Trump has nominated as ambassador to Iceland, may have been said in half-hearted terms, but they are insulting to Iceland and Icelanders, who have had to fight for their freedom and have always been a friend of the United States,” the petition reads. It goes on to urge Gunnarsdóttir to “reject Billy Long as ambassador to Iceland and call for the United States to nominate another man, who will show Iceland and Icelanders more respect.”

Iceland’s Ministry of Foreign Affairs itself asked the U.S. for clarification on Long’s reported remarks prior to the nominee’s apology, telling Politico in a statement that “the Ministry for Foreign Affairs has contacted the U.S. Embassy in Iceland to verify the veracity of the alleged comments.”

Looming over Long’s joke and the outcry it prompted are Trump’s repeated threats to take over Greenland, an autonomous island territory within the Kingdom of Denmark, and his Administration’s suggestions that the use of force could be on the table in the President’s push to acquire the island. 

Greenland, Denmark, and several other European countries have pushed back strongly against the annexation threats. A coalition of top European leaders signed a joint statement declaring Greenland’s sovereignty, while Denmark is increasing its military presence in the territory and European countries including France and Germany have sent small contingents of troops to the island in a show of support. 

The Danish Prime Minister has said that U.S. intervention in Greenland would be the end of the North Atlantic Treaty Organization (NATO), of which both Denmark and the U.S. are founding members.  

“We are now facing a geopolitical crisis, and if we have to choose between the United States and Denmark here and now, we choose Denmark,” Greenland’s prime minister Jens-Frederik Nielsen said in a news conference on Tuesday.

While a number of members of Trump’s own party in the U.S. have also been publicly critical of the push to acquire the territory, Republican Rep. Randy Fine of Florida introduced a bill to make Greenland the 51st U.S. state earlier this week.

Trump also previously expressed a desire to annex Canada and make it the 51st state.