The name given to the SPECTRE rocket in the script for You Only Live Twice. It is also code-named Bird 1 on its final mission. The instrument by which Ernst Stavro Blofeld (Donald Pleasence) plans to aid the Red Chinese by igniting World War III between the United States and the Soviet Union, the Intruder is designed to literally swallow enemy space capsules. Equipped with an electronically operated snout that opens like the mouth of a whale, the Intruder performs effectively, capturing one Soviet and one US Jupiter spacecraft. Having snatched the ships from orbit, the Intruder then returns to its secret rocket base, hidden inside the cone of an extinct Japanese volcano.
On its third mission to capture a second Jupiter spacecraft, a hostile act that the Americans will be led to believe is precipitated by the Russians (this time, the Intruder is emblazoned with the Red star of the Soviet Union to further mislead US authorities), James Bond (Sean Connery) is able to break into Blofeld’s rocket base and activate the self-destruct mechanism on the Intruder before it accomplishes its mission.
The idea of playing the Russians and Americans off against one another is typical of SPECTRE, which had initiated another such caper in From Russia with Love. And when the earlier film’s screenwriter, Richard Maibaum, joined forces with You Only Live Twice director Lewis Gilbert on The Spy Who Loved Me, they went back to the same premise again, only this time billionaire Karl Stromberg (Curt Jurgens) replaced Blofeld as the megalomaniac who’s intent on provoking war between Russia and the West for his own selfish gain. The submarine-swallowing supertanker of that film—the Liparus—was simply a seaborne version of the Intruder rocket.