In a way, one can look upon The Day After as an unplanned part two also, it was broadcast the very next year.

We assume there was a nuclear war.
However according to articles on the movie. This was actually a mystery supposed to be answered in part two, a movie that never got made. Don't know why

WARNING: SPOILERS
In some ways the ending of WW3 was more shocking than The Day After. Before TDA, there had been so much political controversy surrounding it(Reagan's risky foreign policy towards the Russians) that by the time it was finally broadcast, a lot of the shock value was diluted.
With WW3, there was almost no controversy at all. It was featured as the cover story for TV Guide magazine but other than that, nothing. Throughout most of the mini-series, it came across as a low budget remake of Ice Station Zebra. It was only in the last half hour that things began to slide towards unthinkable inevitability and that went so fast by the time the credit roll, you were left stunned
.

well, i wished they should have shown at least some stock footage of missiles going off ala the day after movie. copying the movie "failsafe" ending type was silly and not original.

The ending?
Its doomsday.
Its that man again!!

.If I remember right they showed what looked like a sunset but could have easily have been the light from a distant nuclear explosion.
TAG LINE: True genius is a beautiful thing, but ignorance is ugly to the bone.

What happened at the end? doomsday? all you see is photoof cities; then?
Yes, that's right.
SPOILER!
We know the missiles are flying, but they don't show those. Instead, they have a bunch of musical instruments making wierd chords while we get shots of people staring at the sky. Obviously they didn't have a decent budget for special effects.

In the last 10 minutes or so, the Russian Desant unit takes over the oil valve station in Alaska. Brian Keith's character, Party Secretary Gorny, is assassinated by a car bomb. Rock Hudson's character President McKenna has a phone conversation with the KGB guy Rudinsky, and each leader promises to "stand down." But after both leaders are off the phone, each one orders a nuclear strike because they know the other was lying. The very last images are a series of shots of American and Russian citizens and locales, kind of like the series of photo shots at the end of Fail Safe, but you don't actually see any nukes go off.