Watch Under Siege for Free: How to Stream the Movie Online at 123Movies. . Terrorists launch an attack against the USA. Their first strike is by a suicide squad that detonates a truckload of explosives at an army base in Washington DC. FBI probes indicate that the attack is by Arab terrorists led by Iranians. Subsequent attacks are via airplanes exploded in mid-air, crowded restaurants, and an attack on a mall. Administration cabinet heads push the President to retaliate. The director of the FBI believes that there may be more to the story than the investigation has revealed and the Secretary of Defense is the only other person urging caution.