Its about a group of non related characters that go about thier lives in the midst of growing tensions between US and USSR. One works in an underground nuclear warhead facility, one is a doctor, one is a college student, one is about to get married.
It has some well known actors in it including John Lithgow and the actor from the Police Academy movies, who i believe his name is Steve Guttenberg.
It sounds very similar to the title, Day After Tomorrow but it isnt that, as thats a recent disaster movie