The story behind Clinton's trip to North Korea

WASHINGTON (CNN) -- It took a U.S. former president with global celebrity status to free two American journalists from a North Korea prison.

Laura Ling and Euna Lee arrived back in the United States Wednesday morning with former President Bill Clinton, who flew to North Korea to negotiate their release after they were sentenced to a labor camp.

Iain Clayton said Wednesday that his wife, Laura, told him through a telephone conversation that the North Koreans were willing to grant the two journalists amnesty if a high-level envoy, such as former President Clinton, were willing to travel to Pyongyang.

But there was no shortage of envoys ready to travel to North Korea and negotiate the women's release.

Some heavyweights were turned down by the North Koreans: former Vice President Al Gore, a co-founder of the media outfit the women were working for when they were arrested, and New Mexico Gov. Bill Richardson, a former U.S. ambassador to the United Nations whose previous missions to North Korea included negotiating the release of a detained American.

Lower-level envoys such as former U.S. ambassador to South Korea and current Korea Society Chairman Donald Gregg, Sig Harrison, an expert on North Korean nukes who has traveled there several times, and Han Park, a scholar at the University of Georgia, all offered their services.

Sen. John Kerry, chairman of the Senate Foreign Relations Committee, was also closely involved in coordinating efforts with the White House and State Department to free the women.

According to sources intimately involved with the efforts, Sen. John Kerry -- chairman of the Senate Foreign Relations Committee -- received an official invitation to visit Pyongyang to facilitate their release and open a larger dialogue on the nuclear issue after several weeks of quiet direct diplomacy between Kerry and his aides and North Korea.