Kilo class is the NATO reporting name for a type of military diesel-electric submarines that are made in Russia. The original version of these vessels is designated in Russia Project 877 Paltus (Turbot). There is also a more advanced version, which is designated in the west Improved Kilo and in Russia as Project 636 Varshavyanka. The Kilo will be succeeded by the Lada class submarine, which began sea trials in 2005. The boats are mainly intended for anti-shipping and anti-submarine operations in relatively shallow waters. Kilo class submarines can operate very quietly. Project 636, sometimes called by the US Navy "The Black Hole" for its uncanny ability to "disappear", is thought to be one of the quietest diesel-electric submarine classes in the world.