Mr. Routh, a former roofing contractor from Greensboro, N.C., was interviewed by The New York Times in 2023 for an article about Americans volunteering to aid the war effort in Ukraine. Mr. Routh, who had no military experience, said he had traveled to the country after Russia’s invasion and wanted to recruit Afghan soldiers to fight there.

In a telephone interview with The New York Times in 2023, when Mr. Routh was in Washington, he spoke with the self-assuredness of a seasoned diplomat who thought his plans to support Ukraine’s war effort were sure to succeed. But he appeared to have little patience for anyone who got in his way. When an American foreign fighter seemed to talk down to him in a Facebook message he shared with The New York Times, Mr. Routh said, “he needs to be shot.”

In the interview, Mr. Routh said he was in Washington to meet with the U.S. Commission on Security and Cooperation in Europe, known as the Helsinki Commission “for two hours” to help push for more support for Ukraine. The commission is led by members of Congress and staffed by congressional aides. It is influential on matters of democracy and security and has been vocal in supporting Ukraine.

Mr. Routh also said he was seeking recruits for Ukraine from among Afghan soldiers who had fled the Taliban. He said he planned to move them, in some cases illegally, from Pakistan and Iran to Ukraine. He said dozens had expressed interest.

A man with the same name and similar age as Mr. Routh was arrested in 2002 in Greensboro, N.C., after barricading himself inside a building with a fully automatic weapon, according to the Greensboro News & Record newspaper.

In a May 2020 post, he invited Kim Jong-un, the North Korean leader, to Hawaii for a vacation and offered to act as “ambassador and liaison” to resolve disputes between the two nations.