A nuclear navy, or nuclear-powered navy, refers to the portion of a navy consisting of naval ships powered by nuclear marine propulsion. The concept was revolutionary for naval warfare when first proposed. Prior to nuclear power, submarines were powered by diesel engines and could only submerge through the use of batteries. In order for these submarines to run their diesel engines and charge their batteries they would have to surface or snorkel. The use of nuclear power allowed these submarines to become true submersibles and unlike their conventional counterparts, they became limited only by crew endurance and supplies. Nuclear-powered aircraft carriers Currently, only the United States and France possess nuclear-powered aircraft-carriers. The United States Navy has by far the most nuclear-powered aircraft carriers, with ten carriers and one carrier in service. The last conventionally-powered aircraft carrier left the U.S. fleet as of 12 May 2009, when the USS Kitty Hawk was deactivated. France's latest aircraft carrier, the , is nuclear-powered. The United Kingdom rejected nuclear power early in the development of its s on cost grounds, as even several decades of fuel use costs less than a nuclear reactor. Since 1949 the Bettis Atomic Power Laboratory near Pittsburgh, Pennsylvania has been one of the lead laboratories in the development of the nuclear navy. The planned indigenous Chinese carriers also feature nuclear propulsion. Nuclear-powered submarines The United States Navy operates the largest fleet of nuclear submarines. Only the United States Navy, the Royal Navy of the United Kingdom, and France's Marine Nationale field an all-nuclear submarine force. By 1989, there were over 400 nuclear-powered submarines operational or being built. Some 250 of these submarines have now been scrapped and some on order cancelled, due to weapons reduction programs. Russia and the United States had over one hundred each, with the United Kingdom and France fewer than twenty each and China six. The Indian Navy launched their first indigenous nuclear-powered submarines on 26 July 2009. India is also operating one nuclear attack submarine with talks of leasing one more nuclear submarine from Russia. India plans to build six nuclear attack submarines and follow on to the Arihant class of ballistic missile submarines. Nuclear-powered cruisers The US had several nuclear cruisers. The cruisers were the USS Bainbridge, USS California, USS Long Beach, USS Truxtun, USS South Carolina, USS Virginia, USS Texas, USS Mississippi, and USS Arkansas. The Long Beach was deemed too expensive