Are there any army-related LEGO toys?
LEGO does not directly create military sets.

A LEGO representative gave the following reason:


  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.
  
  -- Gizmodo - Everything You Always Wanted to Know About Lego


There have been some sets that have been military-based though.

The 7595-1: Army Men on Patrol is based on characters from a movie series which are based a military toy.



A number of Indiana Jones sets have some military people and vehicles that in the movie are considered military vehicles. Notably missing though is the tank from the tank scene in Indiana Jones and The Last Crusade.

The Dino Attack theme (or Dino 2010 internationally) also has a tank and a helicopter modeled after military vehicles.