The 27th Day

Five different people from five different countries suddenly disappearing from view. They have been gently abducted by the agent of a faraway dying planet, who gives each of the five earthlings a "killing capsule" that will destroy everything on Earth and allow the residents of the alien planet to re-colonize the planet--but which will be ineffective if not used after 27 days. In typical Cold War fashion, the representatives of the "good" countries refuse to utilize the capsules, while the Soviets, intend to deploy the capsules for their own nefarious purposes. Their perfidy only results in the utter decimation of the USSR. (Source Hal Erickson, All Movie Guide)