Green and the other Slitheen declare a matter of national security and request that the United Nations release the activation codes to launch a nuclear strike against a fictitious mothership. The Doctor realises that the Slitheen actually plan to fire the weapons against other countries in order to start World War III. The Slitheen plan to sell the Earth's radioactive remains as a fuel source, which they have already begun advertising through the signal. Through Harriet's insistence, the Doctor helps Mickey to hack into the controls of a Royal Navy submarine and fire a missile at 10 Downing Street, even though the Doctor is unsure whether they will survive. The Slitheen are caught in the explosion when the missile hits but the Doctor, Rose, and Harriet all survive. With the Prime Minister dead, the Doctor suggests that Harriet could become Prime Minister.