The chronology of the events leading up to the war is depicted entirely via television and radio news broadcasts, and characters' reactions to them. The Soviet Union is shown to have commenced a military buildup in East Germany (which the Soviets insist are Warsaw Pact exercises) with the goal of intimidating the United States (and Great Britain and France) into withdrawing from West Berlin. When the United States does not back down, Soviet armored divisions are sent to the border between West and East Germany.
During the late hours of Friday, September 15, news broadcasts report a "widespread rebellion among several divisions of the East German Army." As a result, the Soviets blockade West Berlin. Tensions mount, and the United States issues an ultimatum that the Soviets stand down from the blockade by 6:00 a.m. the next day, and noncompliance will be interpreted as an act of war. The Soviets refuse, and the President of the United States orders all U.S. military forces around the world on DEFCON 2 alert.
On Saturday, September 16, NATO forces in West Germany invade East Germany through the Helmstedt checkpoint to free Berlin. The Soviets hold the Marienborn corridor and inflict heavy casualties on NATO troops. Two Soviet MiG-25s cross into West German airspace and bomb a NATO munitions storage facility, also striking a school and a hospital. A subsequent radio broadcast states that Moscow is being evacuated. At this point, major U.S. cities begin mass evacuations as well. There soon follow unconfirmed reports that nuclear weapons were used in Wiesbaden and Frankfurt. Meanwhile, in the Persian Gulf, naval warfare erupts, as radio reports tell of ship sinkings on both sides.
Eventually, the Soviet Army reaches the Rhine. Seeking to prevent Soviet forces from invading France and causing the rest of Western Europe to fall, NATO halts the Soviet advance by airbursting three low-yield tactical nuclear weapons over advancing Soviet troops. Soviet forces counter by launching a nuclear strike on NATO headquarters in Brussels. In response, the United States Strategic Air Command begins scrambling B-52 bombers.
The Soviet Air Force then destroys a BMEWS station at RAF Fylingdales, England and another at Beale Air Force Base in California. Meanwhile, on board the EC-135 Looking Glass aircraft, the order comes in from the President of the United States for a full nuclear strike against the Soviet Union. Almost simultaneously, an Air Force officer receives a report that a massive Soviet nuclear assault against the United States has been launched, stating "32 targets in track, with 10 impacting points." Another airman receives a report that over 300 Soviet ICBMs (intercontinental ballistic missiles) are inbound. It is deliberately unclear in the film whether the Soviet Union or the United States launches the main nuclear attack first.
The first salvo of the Soviet nuclear attack on the central United States (as shown from the point of view of the residents of Kansas and western Missouri) occurs at 3:38 p.m. Central Daylight Time, when a large-yield nuclear weapon air bursts at high altitude over Kansas City, Missouri. This generates an electromagnetic pulse that shuts down the electric power grid to any remaining of nearby Whiteman AFB's operable Minuteman II missile silos and of the surrounding areas. Thirty seconds later, incoming Soviet ICBMs begin to hit military and population targets. Kansas City, Sedalia, and all the way south to El Dorado Springs are blanketed with ground burst nuclear weapons. While the story provides no specifics, it strongly suggests that America's cities, military, and industrial bases are heavily damaged or destroyed. The aftermath depicts the central United States as a blackened wasteland of burned-out cities filled with burn, blast, and radiation victims. Eventually, the U.S. President delivers a radio address in which he declares there is now a ceasefire between the United States and the Soviet Union (which, although not shown, has suffered the same devastating effects) and states there has not been and will not ever be any surrender by the United States.