this system, all that is required of the infantryman is to look through an amplifying optical sight and keep it exactly aligned with the objective. During this time, a second electro-optical system mounted parallel to the sight visually receives thermal radiation (generally infrared) from a pyrotechnic system located on the tail of the missile and focuses it on a sensitive receiver / locator. This continuously measures via a computer the position of the heat source (the missile) in relation to the line of sight fixed on the objective, any deviation automatically causing the desired correction signal, which is in turn transmitted along wires (connecting the missile to the launcher) and that without any intervention by the operator. Variants Dragon The basic missile, the M222 missile, weighs 11.5 kilograms and is 744mm long in a 1154mm long launch tube. The fairly basic warhead can penetrate 330 mm of armor plate. Dragon II Dragon II is a simple warhead upgrade, originally called "Dragon PIP" and officially known as MK1 MOD0. The Dragon II received a new warhead that offers an 85% increase in penetration, to about 600mm. Weight increased to 12.3 kilograms and length to 846mm. Dragon II entered service in 1988. Dragon III A further improved Dragon II, the Dragon III received an even more powerful tandem shaped charge warhead, reportedly a Dragon II head with additional precursor charge. Exact penetration remains unknown, though it is claimed to be "several hundred millimeters" better than the SMAW's 600 mm pen HEAA rocket. Additionally, the motor is improved, allowing the missile to reach a range of 1,000 meters in 6.5 seconds, much faster than the original missile's 11 second flight time. The improved motor increases the range as well, propelling Dragon III to 1,500 meters. The second final improvement is a new combined day/night tracker with laser guidance. Only the United States Marine Corps bought this variant, beginning in 1991, while the Army opted to wait for Javelin to enter service. Saeghe Iran has reverse-engineered a version of the Dragon, the Saeghe. They displayed it in 2002 at the Defendory exhibition in Athens, when it was in mass production. Hezbollah has acquired Saeghes for anti-tank and anti-armor uses. Known versions include Saeghe 1, a copy of Dragon II and Saeghe 2, a copy of Dragon III. Saeghe 3 is not confirmed to exist and Saeghe 4 is believed to use a thermobaric warhead.