The reduction in the mass of nuclear warheads allowed full coverage of the entire Sino-Soviet land mass, and the missile control capabilities were also upgraded. The Titan I would be fully independent in controlled flight from launch to the ballistic release of the warhead, which would descend to its target by the combination of gravity and air resistance alone. In May 1955 the Air Material Command invited contractors to submit proposals and bids for the two stage Titan I ICBM, formally beginning the program. In September 1955, The Martin Company was declared the contractor for the Titan missile. In early October the Air Force's Western Development Division was ordered to start work. The Titan was developed in parallel with the Atlas (SM-65/HGM-16) ICBM, serving as a backup with potentially greater capabilities and an incentive for the Atlas contractor to work harder. Martin was selected as the contractor due to its proposed organization and method of igniting a liquid fueled engine at high altitude.