FGM-148 Javelin

The FGM-148 Javelin is an American man-portable anti-tank guided missile and is used as a fire-and-forget weapon.

Call of Duty 4: Modern Warfare
The FGM-148 Javelin appears exclusively in the single-player campaign, most notably in the missions, "The Bog" and "Heat". It can also be found in "Safehouse", and "All In". It can't be fired in enclosed spaces, or a message telling you that there isn't enough room will appear. Also, when it is fired so that the missile ignites near a friendly A.I, the the player will fail the mission and a message will show up on the screen saying, "Friendly fire will not be tolerated!" This is probably due to the fact that the missile igniting burns the teammate, but the teammate in question does not actually die. Occasionally, such as in "Heat," the Javelin missile can get 'hung up' on a roof if fired too close, due to the missile not having the chance to ignite.

Singleplayer
The FGM-148 Javelin returns in Call of Duty: Modern Warfare 2. In the campaign, the Javelin first appears in the level "Of Their Own Accord", where the player is tasked to sniping Russian soldiers armed with Javelin launchers. The player gets an opportunity to pick up a Javelin and destroy Russian armor and attacking Mi-28 gunships with it. The Javelin later appears in "Loose Ends", where Archer and Toad uses one to destroy Ultranationalist vehicles.

Multiplayer
The Javelin is the second to last launcher obtained, being unlocked at level 50. It functions similarly to the Stinger, but has a more sophisticated targeting system: vehicles can be targeted behind cover with arrows pointing to their location. A short beeping noise will confirm when the player has a solid lock on the vehicle. This effectively allows the player to fire in cover, providing there is enough room to fire the rocket. It can shoot down attack helicopters and UAVs in a single hit and the Pave Low in two, or sometimes even in only 1 if it tricks the Pave Low or if it has already deployed its flares. The Javelin can destroy enemy Harriers, although due to the size of the Harriers fuselage, the Javelin missile may miss and then turn and try to destroy the harrier in mid-air. Sometimes, the Javelin Missile, if deterred by flares, will fly up and lock onto another kill streak reward (apart from UAV's, Counter-UAV's or AC-130's) and hit it. This is useful if the targeted kill-streak reward is close to the original target, as it can get a double streak kill. If a Javelin is launched but is beaten to its target by, say, the faster Stinger and no other target remains, it will circle the area with sharp turns and then crash down on the level in a highly unpredictable fashion. Unfortunate players may find themselves committing suicide or Team Killing to no fault of their own. More fortunate players can be rewarded by a highly unexpected random kill on a target far beyond the line of sight. This risk (or chance, depending on which end of the missile you end up) is, for obvious reason, compounded on smaller levels.

However, it has a second function which the Stinger does not have: the Javelin is able to lock onto areas on the ground, effectively making it a sophisticated, shoulder-fired mortar. Once fired, the missile will fly upwards and hit the target area several seconds afterwards, unleashing a fairly large and lethal explosion, similar to, yet smaller than that of the Predator Missile killstreak. When used properly and tactically, a Javelin-user can fire at a safe range and hammer down on a group of enemies. Because of the nature of the weapon, it will always hit the target from above, so make sure your target has line of sight to the sky (in fact, this can even allow you to hit locations that would normally be sheltered against launchers, such as walled-in rooftops, buildings with derelict roofs, or even skylights on Terminal). However, using Danger Close can increase the radius and lethality of the explosion. It is worth noting that the delay between firing and impact is considerable, even a hindrance to reliably getting kills, so it is recommended to use it more as an anti-camp solution or against high traffic objectives like bomb sites or domination nodes. When firing the Javelin, however, the user must be careful to have enough vertical clearance as the rocket will fly forward a short distance then straight upwards. If there is a roof or overhang above and in front of the user, the Javelin will detonate, killing the user and enemies around them. Less frequently, some teams or single players will launch Javelin missiles at the start of a match on a specific area of a specific map or an objective in hopes of killing small or large groups of enemy players.

To summarize, it is important to remember that the Javelin is, in every aspect, a highly tactical weapon. One must consider every dimension of ones own location and that of the intended target ahead of firing:
 * Making certain there is no obstacle directly in front or above oneself. A rule of thumb is to consider that anything in range of a would-be knife attack is probably much too close to be considered safe. The Javelin may not allow locking on to targets which are too close, but the launcher has no safeties against firing into a wall if the player moves after achieving lock. It should also be noted that slight slopes can be treacherous as they may not look like obstacles yet can still cause the missile to slam into the ground before firing its engine, killing you. The Javelin becomes more unpredictable the worse the latency is, as a bad latency means that where you think you are and where the server decides you are may not be the same place. Walls and hills may not be as far away as they seem.
 * As mentioned, making certain that the target is not beneath a roof. Apart from roofs some other less obvious obstacles can cause problems: The crane on Salvage or the raised highway on Underpass are notable examples. Even so, such targets are not necessarily unreachable: a Javelin targeted just outside of a door to an inside area can still have a blast radius stretching far inside, killing targets who believe they are safe.
 * Attempt to anticipate the location of ones targets. Memorize how areas on the minimap relate to areas on the level: pushing start allows you to view the map in its entirety and show you where the enemy seems to be clustered or dug in. Make use of any UAV you or your teammates have called in.
 * Finally, remembering the fourth dimension: time. The Javelin takes time to ready: it is not a reflex weapon. If an enemy spots you aiming it before you have achieved lock-on, your best bet may be to duck down and switch back to your primary. (This applies to Kill Streaks too!) Remember that the Javelin requires longer time to both lock and reach it target than does the Stinger: fire from cover whenever possible.

Unfortunately, while the Stinger missile comes with two missiles upon spawning, the Javelin only has one, making shooting killstreaks like Pavelow and Chopper Gunner more difficult since those require two missiles (the first missile to expend its defensive flares). The Javelin has an unusual loading behavior. A user can actually carry 2 missiles, one in reserve and one in the launcher. After spawning, the player's missile is actually in the reserve slot. Upon drawing the weapon for the first time, the missile is loaded into the launcher, opening the reserve slot. Additional missiles can only be acquired if the reserve slot is open. Because of this using Scavenger and the Javelin can be a little confusing. The player must draw the launcher and let the reload complete at least once to get a second missile. After firing, the Javelin will switch back to the primary weapon without reloading. This means that after firing the launcher, a reserve missile, if present, will NOT be loaded into the launcher by default which means the reserve slot will remain full, which means running over an ammo bag will NOT increase the user's missile count to two. The user must switch back to the Javelin, wait for the long load animation to complete, then run over the ammo bag to pickup the second missile. The Scavenger perk does NOT give the Javelin more starting ammo, however the player can run over Scavenger packs at the start to gain the extra rocket if needed.

The Javelin can be useful for different scenarios besides scoring random kills and destroying air support. In objective game modes like demolition, one can get to a high point and use it on a bomb site if defenders are flooding to the area to disarm it. An example would be Highrise. Get to the top of the office building or the top of the crane outside the buildings and shooting it from there will give you more space to shoot from and have a wider range of options to shoot the missile at. A map more suited for this would be rust as the small, open areas and big lethal explosion radius increase the chance of a kill or two.

The Javelin can be highly lethal in Hardcore both because it kills more readily and because players tend to move less, giving the missile a larger time window in which to reach them, but it can also prove disastrous if the player does not take the risk of Team Killing into account. Once launched, the teammates of the player who launched the Javelin have no way of knowing where it is heading. They will have to rely on the player aiming it correctly in the first place and not targetting either where they are or where they are clearly heading! Pressing Start and checking the minimap ahead of firing is vital to avoid excessive fratricide.

Modern Warfare: Mobilized
The Javelin makes an appearance in Call of Duty: Modern Warfare: Mobilized as one of the three launchers in game, the other two being the RPG-7 and the Explosive Tip Crossbow. In game, the Javelin is available exclusively to single player, though used more extensively than on the console versions. The Javelin is only used in the levels Interception and Hostile Territory. Upon firing the Javelin, the ADS button on the touch screen disappears, preventing one from using the ADS until a fresh rocket is loaded.

In terms of function and power, it is the same as the console versions, but it differs slightly in appearance. Possible targets are shown in black boxes instead of green, there are no arrows pointing to the targets that are out of view, there is a yellow cross-hair on the screen, and there is no restriction to where it can be fired. But when fired in an enclosed area, the player can kill or injure themselves.

Trivia

 * In Modern Warfare: Mobilized while aiming through the sights if you get hurt your HUD will be gone except for crouch/stand.
 * You can actually hold your breath while using the Javelin, just like sniper rifles. If you hold Shift and press "switch weapon" the environment and your will get a bit lowered. However, this does not lessen the noise of your gun for other players and your shots will appear as a red dot on mini-map.
 * The Javelin will occasionally miss enemy air support. In some instances, it can go right through enemy Harriers.
 * When attacking enemy aircraft, the Javelin will light up the "DIR" circle, or "direct attack" option. This means the missile should fly straight at the vehicle. However, the missile still follows the top-attack trajectory.
 * In Modern Warfare 2, the Javelin has writing on the plaque under the scope. The writing is an Easter egg to Infinity Ward.
 * In real life, the Javelin has thermal vision. Unlike in the game, it has a colored screen.

Glitch
As of the December 11th Patch, this Glitch has been fixed for all Systems.thumb|right|300px|New Javelin on a mounted minigun glitch.

Upon release of Modern Warfare 2, there was a very popular glitch which was typically called the Javelin Glitch. Many players had abused the glitch. It has successfully been removed from the PC, Xbox 360, and PlayStation 3 version. This glitch worked with all Launchers except the Thumper, likely due to its required detonation range.

The glitch involved having any equipment aside from a Frag Grenade, and any launcher (except the Thumper) equipped; the user had to have the Launcher as their current weapon; they would then hold the equipment button, switch back to their Launcher, and run around the map waiting to be killed, when the glitch would execute.

When the glitch was used, upon the user's death, a live missile would immediately fall out of the launcher and detonate on the ground. Given the very large blast radius of launchers it was generally an instant kill. To counter the glitch, players would attempt to kill the glitchers at a distance from themselves and/or their teammates. As an alternative, players would try running away, or, as a last resort cooking a frag grenade/sticking a semtex/shooting your feet with an RPG-7 when the glitcher got close. This would still result in a suicide but the shooter would receive a kill, where as the glitcher would not; however a keen sense of timing was necessary to pull it off successfully. The "Javelin Glitch" was typically executed in such a way that - regardless of death or injury - the user would receive a kill, by means of standing within proximity of enemy players so the explosion connected. The perks Marathon, Lightweight (or Danger Close), and Commando were often used to exploit it further, which allowed for users to sprint infinitely and move around at a fast pace, melee knifing the unaware, and "exploding" in front of those who happened to spot them. It was also possible to kill a glitcher during the knife swing animation to avoid the glitch occurring as the launcher is not considered the active weapon during that time and will not fire.

However, a new glitch has been discovered that involves the Javelin. The glitcher equips the Javelin and uses any Minigun. The glitcher then spins the barrel using the zoom button, and the Javelin lock-on sound is heard. The glitcher then fires and a Javelin rocket is emitted. This glitch is not all that helpful, though, because the Javelin can be fired anyway, and the Minigun will not affect it in any way more so it seems that it is simply used as comic relief at times.