A team of U.S. nuclear experts began a rare visit to North Korea on Tuesday to examine ways of disabling the country's main nuclear complex under an international accord.

The seven-member delegation crossed into the North by land from the border village of Panmunjom around 11 a.m., said David Oten, spokesman for the U.S. military in South Korea.

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They will join two nuclear experts from China and Russia who plan to fly to Pyongyang for a joint survey.

During a five-day visit, the three-nation team plans to visit North Korea's main nuclear complex at Yongbyon, 60 miles north of Pyongyang. The North has shut down the country's sole functioning nuclear reactor at Yongbyon. The deal calls for Pyongyang to permanently disable the facility in exchange for economic aid and political concessions.

In recent bilateral talks with the U.S., the North promised to complete the disablement by year's end.

The North's invitation of outside nuclear experts — the first since July, when U.N. nuclear inspectors verified the shutdown of the Yongbyon reactor — is considered a strong indication it is serious about following through with its denuclearization commitments.

South Korea's deputy nuclear negotiator, Lim Sung-nam, said the trip would not result in an agreement on how to disable the facilities because the experts were only there to survey the sites and get an idea of the actions needed to dismantle them.

The experts would deliver their findings at the next round of six-nation talks, when an agreement on disabling the facilities was likely, he said.

The six nations — the two Koreas, the U.S., Japan, Russia and China — agreed at their last meeting in July to meet again in September.

The February deal came after more than three years of on-again, off-again negotiations during which North Korea conducted its first-ever nuclear test detonation in October.

Under the deal, North Korea also agreed to fully disclose all its nuclear activities.

Complete coverage is available in FOXNews.com's North Korea Center.