Mr. Obama did not speak directly with Mr. Clinton before the mission. But his national security adviser, Gen. James L. Jones, contacted the former president to sound him out. The senior official said the administration did “due diligence” with the North Koreans to ensure that if Mr. Clinton went, he would return with the journalists. He also denied that Mr. Clinton apologized as a condition of obtaining the pardons from the government.

Image Former President Bill Clinton waved before boarding a plane at an airport in Pyongyang. Credit... Zhang Binyang/Xinhua, via Reuters

As president, Mr. Clinton had sent Mr. Kim a letter of condolence on the death of his father, Kim Il-sung, according to a former official. For Mr. Kim, the former official said, freeing the women was a “reciprocal humanitarian gesture.”

Mr. Kim is believed to have suffered a stroke last year. American officials said they thought his declining health had set off a succession struggle, complicating the Obama administration’s dealings with the North.

The families of the American journalists issued a statement saying they were “overjoyed” by news of the pardon and thanked Mr. Obama and Mrs. Clinton. “We especially want to thank President Bill Clinton for taking on such an arduous mission and Vice President Al Gore for his tireless efforts to bring Laura and Euna home,” the statement said.

Current TV said in a statement that it too was “overjoyed” and that the hearts of its employees went out to Ms. Ling and Ms. Lee for “persevering through this horrible experience.”

The Obama administration said Ms. Ling and Ms. Lee were in good health.

Administration officials said Mr. Clinton went to North Korea as a private citizen, did not carry a message from Mr. Obama for Mr. Kim and had the authority to negotiate only for the women’s release.

“This was 100 percent about the journalists,” said a senior administration official, who spoke on the condition of anonymity because of the delicacy of the matter. “We knew Kim Jong-il would probably seek a meeting with Clinton. But that’s not what this visit was about.”