Trivia: When Ben Peterson is killed by a giant ant, he emits a high-pitched, half-choked death scream. This scream has been used in many other movies ever since: in Small Soldiers (when Brick Bazooka loses his legs); in Star Wars - A New Hope, when Luke shoots a stormtrooper in the shaft-swinging scene; in Lord Of The Rings - The Two Towers, when an Elf warrior is thrown off the Helm's Deep wall; and in Lord Of The Rings - Return of The King, when a Gondor soldier fleeing from Osgilliath is snatched up and dumped by a Nazgul steed. I guess that makes it the most used death scream in movie history.
Trivia: Leonard Nimoy has a uncredited appearance as an army sergeant at the hospital.
Answer: Like the General said, the less people that know about the ants the better. They were a special task force assigned with the equipment and deputized to use any and all measures to stop the ants. Since the movies was set in the 1950's, James Arness and James Whitmores were most likely veterans of WW II and Korea.