Lego has no Military related sets in light of the fact that the inventor’s belief that war should not appear as it is something children should love playing with. To this black hole jumped in custom made toy manufacturers (like BrickArms) who 3d print weapons & accessories like M16, AK47, RPG and even have pink weapons collection (Summer 2012 Pink Weapons Pack). Lego has weapons in many different sets, but the weapons Lego manufactures are old (as in the Lego Castle set) or fantasy-oriented (as in the Star Wars set).
Next answer from a Lego Official on Gizmodo.com:
• Are there any chances that Lego will ever start producing modern day warfare Lego, with tanks and helicopters and what not?
We have a strict policy regarding military models, and therefore, we do not produce tanks, helicopters, etc. While we always support the men and women who serve their country, we prefer to keep the play experiences we provide for children in the realm of fantasy.
Other source>> Wikipedia – Lego
Original photos by BrickArms