The Northrop Grumman B-2 Spirit (also known as the Stealth Bomber) is a multirole heavy bomber with "low observable" stealth technology capable of penetrating dense anti-aircraft defenses to deploy both conventional and nuclear weapons. Because of its astronomical capital and operations costs, the project was controversial in Congress and among Pentagon brass during its development and placement into service. In time, Congress scaled back initial plans to purchase 132 of the bombers. By the early 1990s the United States elected to purchase just 21 of the bombers at US$737 million per aircraft. Total program cost averaged US$2.1 billion per aircraft in 1997 dollars.
The B-2 is operated exclusively by the United States Air Force with none in the Air Force Reserves. Though originally designed in the 1980s for Cold War operations scenarios, B-2s have been used in combat to drop bombs on Kosovo in the late 1990s, and see continued use during the ongoing Wars in Iraq and Afghanistan.
Featuring formidable design specifications, a two officer crew aboard the bomber can drop up to eighty 500 lb (230 kg) class JDAM "smart" bombs, or sixteen 2,400 lb (1,100 kg) B83 nuclear bombs in a single pass through extremely dense anti-aircraft defenses. The bomber has been a prominent public spectacle at air shows since the 1990s. It has been the subject of espionage and counter-espionage activity.