800px-B-2 Spirit original

A USAF B-2 in flight.

The B-2 Spirit is an Americam heavy bomber which uses low-observable stealth technology to penetrate anti-air defenses and deliver payloads of either regular of nuclear bombs. This is why it is often referred to as the "Stealth Bomber", but being invisible to UAV and only noticed once nearby due to the loud noise it makes.