Algeria has recently received the two Russian Kilo class diesel-electric submarines they ordered four years ago. The Kilos weigh 2,300 tons (surface displacement), have six torpedo tubes and a crew of 57. They are quiet, and can travel about 700 kilometers under water at a slow and nearly-silent speed of about five kilometers an hour. Kilos carry 18 torpedoes or SS-N-27 anti-ship missiles (with a range of 300 kilometers and launched underwater from the torpedo tubes.) The combination of quietness and cruise missiles makes Kilo very dangerous to American carriers. China, North Korea and Iran have also bought Kilos. Russia is working on a new design (the Lada), but many export customers find the 1980s era Kilo adequate (and cheap, about half what a similar Western boat would cost). Over 55 Kilos have been built or are under construction.