General Dynamics is a defense contractor and business jet manufacturer. The firm's segments are aerospace, marine, combat systems, and technologies. General Dynamics' aerospace segment manufactures Gulfstream business jets and operates a global aircraft servicing operation. Combat systems produces land-based combat vehicles such as the M1 Abrams tank and Stryker armored personnel carrier, as well as munitions. The marine segment builds and services nuclear-powered submarines, destroyers, and Navy support ships. The technologies segment contains two main units: an IT business that primarily serves the government market and a mission systems business that focuses on products that provide command, control, computing, intelligence, surveillance, and reconnaissance capabilities to the military.