The seizure and release of a North Korean ship carrying Scud missiles bound for Yemen highlights two serious international issues: Pyongyang's readiness to export destabilizing weapons and the proliferation of ballistic missiles. The ship and its cargo were released because there was no apparent violation of international law. That is not reassuring. The world needs a more effective arms-control framework to check the proliferation of such missiles -- and North Korea must be a member of such a regime.

Last week's incident was no surprise. United States intelligence had been tracking the North Korean vessel, the So San, since it left Nanpo harbor several weeks ago. It was boarded in the Arabian Sea by Spanish Marines, who then turned the ship over to the U.S. The interdiction was legal both under the terms of the United Nations resolution that authorized the war against terrorism and the Law of the Sea, which allows the crew of a vessel to board another "if the ship is without nationality," i.e., not flying a flag. Although the So San carried Cambodian registration, there was no normal identification on the ship.

Upon inspection, the marines discovered 15 Scud missiles and other weapon-related cargo hidden under sacks of cement. The attempt to hide the shipment, the failure of the crew to identify its nationality and the absence of paperwork aroused suspicions about the weapons' destination until the government of Yemen revealed that it had purchased them. After the U.S. received promises from the Yemeni government that the weapons would only be used for defensive purposes and would not be transferred, the ship was allowed to continue.