A U.S. bomb squad searched a ship Tuesday that was intercepted in the Arabian Sea carrying a dozen Scud-type missiles from North Korea, defense officials confirmed to Fox News.
U.S. officials said the missiles were at least initially headed for Yemen.
The ship was stopped and boarded about 600 miles east of the Horn of Africa, after close tracking by U.S. intelligence, said U.S. officials who spoke on the condition of anonymity.
The ship contained about a dozen short- to medium-range missiles, similar to the Scud missiles used by Iraq in the Persian Gulf War, the officials said. It also contained missile parts.
The Bush administration met the discovery with a measured reaction, declining to characterize either how much concern it raised among U.S. officials or the range of options for a response. A White House spokesman for national security issues said the United States would enlist the help of U.S. allies in the region to fashion its next move -- a decidedly diplomatic, and possibly slow, approach.
"This is an issue of concern," said spokesman Sean McCormack. "We are working with other governments to figure out the next step."
McCormack said the immediate tasks were to deal with the crew, identified as from North Korea, and to secure the ship.
The ship allegedly carrying the missiles was stopped by two vessels from the Spanish Navy participating in Operation Enduring Freedom, the U.S.-led global anti-terrorism coalition, said Alberto Martinez Arias, a spokesman for Spain's Defense Ministry.
Crews from the Spanish ships, the Navarra and Patino, stopped the unflagged ship "Sosan" east of the island of Socotora and called U.S. authorities for assistance, Martinez said. The Spanish Navy stopped and boarded the ship after its crew refused to identify themselves.
The North Korean captain of the Sosan initially told Spanish officials the ship was carrying cement. The Scuds were discovered shortly thereafter, Martinez said.
The ship was being held in the area while the search continued and as U.S. experts, who shortly afterward boarded the vessel, made sure that any explosive materials were neutralized, U.S. officials said. It was not clear where the ship was registered, a senior administration official said.
Officials said the shipment did not appear to be headed for Iraq. However, the senior administration official said that although the ship was headed for Yemen, it was unclear whether it -- and the missiles on board -- had another destination beyond that.
Yemen has been identified by the United States as a nation that has harbored terrorists, although its government has been an ally of the United States in the war against global terrorism. Yemen's port of Aden was the site of the October 2000 attack on the USS Cole by terrorists, which killed 17 sailors.
Yemeni officials contacted late Tuesday said they had no information concerning the ship, its contents or its boarding by international forces.
The boarding of the ship occurred as Defense Secretary Donald H. Rumsfeld was traveling in the area.
It was unclear precisely what missiles were aboard the seized vessel. North Korea has built and exported at least two missiles in the Scud class: the Scud B and the Scud D, or No Dong.
Without providing specifics, the senior administration official said the United States has evidence beyond the identity of the crew to identified the missiles as originating in North Korea.
Scud B missiles were produced in large numbers by the former Soviet Union and ended up in Iraq and North Korea, among other nations. The missiles are very inaccurate, often break up in flight and have a range of less than 200 miles.
The Scud D, or No Dong, missile produced by North Korea is advanced compared with the Scud B. It has a range of about 840 miles and can carry a conventional, chemical or nuclear warhead. Iran and Pakistan use modified versions of the No Dong, and Pakistan's are fitted to carry nuclear warheads.
The Associated Press contributed to this report.