The Ultimax 100 is a Singaporean 5.56 mm light machine gun, eveloped at the Chartered Industries of Singapore - CIS (currently incorporated into the Singapore Technologies Engineering Ltd or ST Engineering company) by a team of engineers under the tutelage of American firearms designer L. James Sullivan. Work on a new light support weapon for the Singapore Army began in 1978. The weapon is produced by CIS (presently STK - Singapore Technologies Kinetics), initially in the Mark 1 version, later - the Mark 2, and currently, only the Mark 3 (a Mark 4 variant is being evaluated). The Ultimax 100 (also called the U 100) is used in significant numbers by the armed forces of Singapore, Croatia and the Philippines.