Kenneth Bae attends a news conference at Joint Base Lewis-McChord in Washington state after being released by North Korea. (Tim Exton/Agence France-Presse via Getty Images)

The top U.S. intelligence official on Sunday described the extraordinary trip he took to North Korea this month to secure the release of two Americans who were taken prisoner there.

James Clapper told CBS's "Face the Nation" that he was "apprehensive" and "not completely confident" that North Korea would release the men when he arrived in Pyongyang.

"We weren't sure how this was going to play out," he said. "I, personally, was not completely confident that they would actually release our two citizens."

Clapper said it's "kind of always been on my professional bucket list" to visit North Korea.

He said he and the group he was traveling with were taken to a guesthouse in the North Korean capital and greeted by the nation's minister of state security. Clapper said he carried a short letter from President Obama that identified Clapper as Obama's envoy and characterized North Korea's willingness to release the two men, Matthew Miller and Kenneth Bae, as a "positive gesture," Clapper said.

Clapper said that he made the point that he was "very interested in recovering our two citizens" and that the North Koreans were disappointed that there wasn't some additional offer or "breakthrough" from the United States. Clapper did not elaborate on what type of offers the North Koreans wanted.

Clapper said that he had dinner with North Korean officials and that they discussed human rights and criticized what they called the United States's "interventionist approach" on the issue and "interventionist policies in their internal matters." He said the North Koreans also made allegations about U.S. involvement in South Korea.

"It was pretty terse," Clapper said of the tone of the dinner. "It wasn't exactly a pleasant dinner."

He said that his group spent the following day waiting and that the two men were ultimately released. The group then left the country.

Clapper said he doesn't know where relations between the two countries are headed.

"Will this perhaps serve as a catalyst or stimulus for more dialogue?" he asked. "I hope so, but I don't know."