Deployed on some USN and RAN warships, the NULKA is a rocket propelled, disposable, offboard, active decoy designed to seduce anti-ship missiles away from their targets. It has a unique design in that it hovers in mid air while seducing the incoming anti-ship missile.

The Nulka consists of the missile itself enclosed in a hermetically sealed canister. This canister is then contained in a Launcher module (as fitted to RAN vessels), or an MK47 Launcher (as fitted to USN vessels).

The word "Nulka" is of Australian Aboriginal origin and means "be quick".