On October 8, 1996, President Clinton signed into law the Maritime Security Act (P.L. 104-239) after it was overwhelmingly adopted by the House of Representatives and the Senate. This measure established the Maritime Security Program (MSP) to support an initial fleet of 47 militarily useful U.S.-flag commercial vessels crewed by American citizens. Participating vessel operators are required to make their ships and other commercial transportation resources available to the Department of Defense during times of war or national emergency. Unlike the operating-differential subsidy program, MSP has few restrictions on vessels operating in the U.S. foreign commerce. Eligible vessels may be built either in the United States or in a foreign country.
Through the enactment of the Maritime Security Act of 2003, the 108th Congress expanded the program to incorporate 60 vessels. The legislation also called for increased payments, subject to annual appropriations. The program is administered on the basis of renewable one-year contracts, provided funding is available.