The Pentagon announced Tuesday it mistakenly shipped part of the triggering mechanism for four nuclear warheads to Taiwan a year-and-a-half ago, and only realized the mistake last week and recovered the material in recent days. But officials say the missile nosecones contained only electrical components and had no nuclear material. VOA's Al Pessin reports from the Pentagon.

US Defense Secretary Robert  Gates at the Pentagon, (file)

The U.S. Air Force cannot say how the mistake happened, but Defense Secretary Robert Gates has ordered a high-level investigation. What officials do know is that the Defense Department shipped four nosecones for Minuteman nuclear missiles to Taiwan in the fall of 2006, containing batteries and electrical fuses that sense proximity to the ground and initiate the missiles' triggering sequence. They say the actual triggers were not shipped, nor were any other missile components or nuclear material.

Officials say the four cylindrical crates containing the missile parts, each about 82 centimeters high and 47 centimeters in diameter, sat in a warehouse in Taiwan until last week. They say Taiwanese officials notified the Pentagon they had received some wrong equipment in response to an order for helicopter batteries. But the U.S. officials say it took time to figure out exactly what the Taiwanese had.

They say once they identified the missile parts late last week they notified Secretary Gates, who issued orders on Friday for the items to be put under U.S. control and returned to the United States. The officials say that has been done and the nosecones are now at a secure facility.

Principal Deputy Undersecretary of Defense Ryan Henry says preliminary indications are that Taiwanese authorities did not examine or tamper with the nosecones, and he says Taiwanese officials "acted very responsibly" throughout the process of identifying and returning the items.

"These are first indications, but our communications with experts indicate that this is a system that was built and designed in the 60s, and so therefore the technology that is in there is quite dated," said Henry. "But nonetheless we're taking this extremely seriously, and we feel quite confident we'll be able to determine if there has been any tampering or exploitation."

Henry says the missile fuses and battery systems were specifically designed for Minuteman missiles and could not be used to help trigger any other weapon. Officials say the material is classified, even though it is outdated.

Henry stressed that the shipment was a mistake, and does not represent any change in U.S. policy toward Taiwan or China. The United States provides Taiwan with defensive military equipment and is committed to help defend the island if it is attacked by China. He says the Chinese government has been informed of the situation, but he would not characterize its response.

This mistake by the U.S. Air Force and the Defense Logistics Agency follows harsh of criticism and a series of changed procedures after an Air Force bomber inadvertently flew six nuclear-armed missiles across the United States last August.

The investigation of the latest incident is being led by a four-star admiral, and officials say Secretary Gates is determined to find out what went wrong and to hold those responsible accountable.