Last year, the US air force was also forced to launch an investigation after one of its B-52 bombers flew across the US last week loaded with nuclear-armed missiles.
George Bush, the US president, has been notified of the mistake and of the recovery of the items, said Ryan Henry, principal deputy under secretary of defence for policy.
Henry, who called the error "disconcerting" and intolerable, said that the Chinese government has been notified of the error.
An examination of the site in Taiwan where the components had
been stored after delivery indicated that they had not been tampered with, he added.
The United States follows a "one China'' policy that recognises there is
a single China and that self-ruled Taiwan is part of it.
However, Washington remains the island's most important foreign backer, providing it with the means to defend itself against a possible Chinese attack.
China and Taiwan split following a civil war in 1949 but Beijing continues to claim the island as part of its territory and has threatened to attack if Taiwan formalises its independence.
It also has about 700 missiles pointed at the island.