U.S. Soldiers -- Life Among the Weeds in Afghanistan

Life isn't all bad for our heroes in uniform in Afghanistan ... especially when they encounter MASSIVE marijuana fields as these photos show ... but we've learned these photos have triggered a military investigation.

A bunch of guys who appear to be soldiers whipped out their cameras ... and their weapons ... and posed for a bunch of pics while out on patrol in Kabul recently.

No word on the identity of the soldiers ... or when the pics were taken. Note -- the photos DO NOT show any of the soldiers smoking the weed, but there is a shot of the guys decorating the inside of their vehicle with cannabis leaves.

We spoke to U.S. Army officials ... who tell us the situation is "being looked into" ... noting, "The U.S. military takes allegations of drug possession, transfer, distribution, and use very seriously."

The Army also notes that Afghan anti-drug units, aided by international security forces, have resulted in a tremendous increase in drug seizures over the past year.

Ironically, the baseball caps 2 of the soldiers are wearing are as problematic as the weed. Soldiers caught wearing non-military issue headgear can get in big trouble.