North Korea has released the two last-remaining American detainees, the U.S. government announced Saturday, a decision seen as aimed at improving Pyongyang's image amid international efforts to punish the regime for human rights violations.

The two -- Kenneth Bae and Matthew Todd Miller -- have been allowed to depart North Korea and are on their way home to re-join their families. Director of National Intelligence James Clapper is accompanying them, his office said in a statement.

Diplomatic sources said that the two have arrived in the U.S. territory of Guam.

Bae, a Korean-American missionary, has been serving 15 years of hard labor after being detained in late 2012 for unspecified anti-state crimes. Miller was detained in April and has since been sentenced to six years of hard labor for committing "hostile" acts.

Their release came after the North freed a third American detainee, Jeffrey Fowle, late last month.

"We welcome the DPRK (North Korea)'s decision to release both Mr. Bae and Mr. Miller. We want to thank our international partners, especially our Protecting Power, the Government of Sweden, for their tireless efforts to help secure their release," the DNI office said.

U.S. President Barack Obama hailed the release, saying it is a "wonderful day" for them and their families. He also said that the U.S. is "very grateful for their safe return." Obama spoke after announcing his pick for attorney general.

In a separate statement, the State Department welcomed the release.

"The safety and welfare of U.S. citizens abroad is the Department of State's highest priority, and the United States has long called on DPRK authorities to release these individuals on humanitarian grounds. We join their families and friends in welcoming them home," State Department spokeswoman Jen Psaki said.

Psaki also praised Clapper, saying he engaged in discussions with North Korean authorities about the release of two citizens on behalf the U.S. government. She did not elaborate on the negotiations, including whether any concessions or rewards were offered to the North.

Psaki also urged U.S. citizens not to travel to North Korea.

South Korea also welcomed the release, and urged the North to free a South Korean missionary, Kim Jeong-wook, held there and take other positive steps to resolve humanitarian issues between the two divided states, such as reunions of families separated by the 1950-53 Korean War.

The North's decision came amid international efforts led by the European Union to adopt a U.N. General Assembly resolution that calls for referring the totalitarian regime to the International Criminal Court (ICC) for human rights violations.

North Korean diplomats have been scrambling to tone down the resolution, offering to invite the special U.N. human rights investigator to visit the country in exchange for the envisioned resolution dropping any mention of referring the issue to the ICC.

They have also stepped up PR activities, including providing a rare briefing on the country's human rights situation for U.N. diplomats, attending a private seminar to make the country's case and speaking more frequently to reporters.

But chances of actual referral of the North to the ICC are slim because U.N. General Assembly resolutions are not legally binding, and the U.N. Security Council is unlikely to approve the resolution because China is sure to exercise its veto power against it.

North Korea has long been labeled as one of the worst human rights violators in the world. The communist regime does not tolerate dissent, holds hundreds of thousands of people in political prison camps and keeps tight control over outside information.

But Pyongyang has bristled at any talk of its human rights conditions, calling it a U.S.-led attempt to topple its regime.

Last month, the North released its own human rights report, claiming the country has the world's most advantageous human rights system and policies.

The North's release could also be an olive branch aimed at restarting the stalled negotiations on its nuclear program. U.S. officials have cited the detention of American citizens as a big stumbling block to improved relations between the two countries.

Six-party denuclearization talks, which bring together the two Koreas, China, Japan, Russia and the U.S., have been stalled since late 2008. Pyongyang has called for unconditional resumption of the talks, but the U.S. has demanded the North first demonstrate its denuclearization commitment if it wants to reopen the sessions. (Yonhap)