South Korean officials said Monday that North Korea had released a South Korean national who'd been attending New York University before his detention, in a possible sign Pyongyang wants better ties with rival Seoul and may back away from a recent threat to launch a long-range rocket later this month.

Seoul's Unification Ministry said Won Moon Joo, 21, was released at the border village of Panmunjom. Joo, who has permanent resident status in the United States, was arrested in April for allegedly illegally crossing the Chinese border into North Korea. His alleged motivation was not clear.

He was enrolled in NYU's Stern School of Business, but had not been taking classes at the time of his capture, according to the university.

North Korea often uses detainees in attempts to win political concessions and aid from rivals Seoul and Washington, and a South Korean analyst said Pyongyang may have calculated that since Joo's alleged crime was relatively minor, his release might boost the impoverished, authoritarian country's international image and lead to more investment and tourism chances.

Last month, Joo was presented to the media in Pyongyang and said he had not been able to contact his family but wanted them to know he was healthy. For most of the 30-minute appearance, Joo read a prepared -- and probably coached -- speech praising the country, its government and people. Other foreigners who have been detained in the North have said after their release that they were coached closely on what to say in such statements.

Joo's release reduces the number of South Koreans known to be held in North Korea to three. All three are accused of more serious espionage acts or attempts to establish underground Christian churches in the country.

The release comes amid speculation that North Korea may not go ahead with an earlier threat to launch what it calls satellites aboard long-range rockets to mark this week's 70th birthday of its ruling party.

A launch would deepen an international standoff. The U.S., South Korea and their allies say North Korea's launches are disguised tests of its long-range missile technology that are banned by the United Nations. Recent commercial satellite imagery, however, showed no signs of preparations at the North's main launch site. South Korean defense officials also have seen no indication of an imminent launch.

The launch plans earlier cast doubt over a possible easing in animosity between the Koreas. In late August they agreed to resume the reunions of families separated by the Korean War after ending a military standoff caused by a mine blast on the border that Seoul blamed on the North. The blast seriously injured two South Korean soldiers.

By freeing a South Korean detainee, North Korea showed it still wants better ties with South Korea and won't likely push ahead with its rocket launch plans, said Koh Yu-hwan, a North Korea expert at Seoul's Dongguk University. He said the planned reunions will likely happen later this month as earlier agreed.

Seoul's Unification Ministry described as "fortunate" the North's decision to release Joo and urged it to free the three others.

The Koreas are divided along the world's most heavily fortified border, a legacy of the 1950-53 Korean War that ended with an armistice, not a peace treaty, thus leaving the peninsula at a technical state of war.

The Associated Press contributed to this report.