When two trains crash in Russia, one of them carrying a nuclear payload, a nuclear explosion follows. White House nuclear expert Dr. Julia Kelly thinks this wasn't an accident and believes that Bosnian terrorists are behind the incident. She is given a smooth talking, irreverent US Army Special Forces officer, Lieutenant Colonel Thomas Devoe, to work with, who has Russian contacts and is convinced that the crash was staged to hide the hijacking of the other warheads on board.

Kelly and Devoe try to track down the terrorists through a trucking company which is a front for the Russian Mafia. When the Mafia realizes they are in fact government agents, they escape, but in the process, Devoe's long time friend and Russian counterpart is killed when three cars with armed Mafia members inside block their car. Devoe's Russian friend exits the car to talk to the men. As he heads back to the car, he is viciously gunned down by one of the armed men. When the truck carrying the warheads is located (using a ruse in which Devoe convinces the driver over the phone that there is a smart bomb falling towards him, causing him to turn out of traffic on a road, so that the truck can be seen in an aerial photo.

Devoe leads a group of US Army Rangers illegally over the Russian border to seize it. In that operation, three helicopters are used, one of them was shot down by Russian SAM battery when they overflew Russian airspace. When the truck is seized, it is found that the trigger bomb from one of the warheads is missing. It is learned that the bomb was taken by a Bosnian, and that it is due to be used to destroy the UN headquarters in New York.

One of the terrorists, Dušan Gavric , is a Yugoslav without identity ("I am a Serb, a Croat, and a Muslim"   in reference to all sides in the war torn former Yugoslavia). He wants to avenge the death of his wife and daughter, who were killed by a sniper in Sniper Alley, Sarajevo. He blames the United Nations for not protecting them and therefore he wants to blow up the United Nations building in New York City.

The denouement of the film takes place in a Catholic church, where the wounded Gavric commits suicide, knowing that the bomb in his rucksack will detonate if Kelly and Devoe try to remove it from him. With seconds to spare, Kelly is able to remove a part of the Beryllium sphere of the bomb, preventing it from triggering a nuclear reaction and limiting the explosion to within the church.