The AH-1G Cobra attack helicopter was developed by Bell as part of a programme to create a specialised attack helicopter. It was first deployed in Vietnam in the autumn of 1967, where it demonstrated its high combat capabilities. To engage ground targets, the AH-1G helicopters utilised both built-in weapons – a six-barrel machine gun or a grenade launcher – as well as externally mounted weapons: unguided rockets, mounted machine guns, and later a six-barrel 20mm cannon. Its firepower allowed it to engage armoured targets as well. Over time, the AH-1G received a number of enhancements, including measures to defend against surface-to-air missiles with thermal guidance. This involved cooling the engine exhaust, and a special pipe was installed on the helicopters to direct the hot gases upwards, into the rotor's rotational plane. After the war, the AH-1G Cobra helicopters continued to be used by units stationed in Western Europe.