A strategic bomber is a medium-to-long-range bomber aircraft designed to drop large amounts of air-to-ground weaponry onto a distant target for the purposes of debilitating the enemy's capacity to wage war. Unlike tactical bombers, penetrators, fighter-bombers, and attack aircraft, which are used in air interdiction operations to attack enemy combatants and military equipment, strategic bombers are designed to fly into enemy territory to destroy strategic targets. In addition to strategic bombing, strategic bombers can be used for tactical missions. There are currently only three countries that operate strategic heavy bombers: the United States, Russia and China.