Russias first Kilo class submarine entered service a quarter century ago, and has since become too cheap and effective to replace. One of the more successful diesel-electric boats in service, 53 have been built so far, and most of them have been exported (to Poland, Romania, Algeria, India, Iran and China). Over the years, there have been several major models of the Kilo. First there was the original Project 877 boats, followed by several improved versions. Russia is selling new Kilos for about $200 million each. The Kilos weigh 2,300 tons (surface displacement) boat with six torpedo tubes and a crew of 57. It is very quiet, and can travel about 700 kilometers under water at a quiet 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. 

Russia designed a successor to the Kilo in the late 1990s (the 1,600 ton Amur class), but has not been able to find any foreign buyers. The Kilo is still considered very good value for the money, especially for countries that cannot buy, for cost or political reasons, the more expensive (up to a billion dollars each) and capable European diesel electric boats. Many admirals have realized that there is not a lot of good anti-submarine capability out there, even in the U.S. Navy. So a cheaper Kilo class boat would probably be just as effective as the much more expensive European subs.