Soviet amphibious capabilities are not limited to the continental theaters of military operations contiguous to the Soviet Union but can be used throughout the world. The evolution of modern Soviet amphibious ship types can be traced to 1916 when the tsarist navy ordered forty 1,400-ton amphibious warfare ships. Submarines and small surface combatants were the first warships to be extensively developed and deployed by the Soviet Navy in the post-Stalin era. Although developments in other areas have been more spectacular, the Soviets continue to regard corvettes and missile, patrol, and torpedo boats and craft as an important part of their navy. The most important characteristic of the Soviet corvettes and missile and patrol boats is the placing of highly lethal weapons on inexpensive, expendable platforms. The mission of the Soviet Navy's corvette and missile, patrol, and torpedo boat forces is to provide coastal security and to defend the maritime approaches to the Soviet Union.