It is not banned by the military. It is not banned because it doesn't do anything. The current Halodrol 50 (manufactured by Gaspari Nutrition) is only similar to H-Drol or Halodrol in name. Pro-hormones were taken off the market in 2009.
The warning is there to entice people to buy the product. It's written there to make you think it might be similar to a pro-hormone or an anabolic. The truth is that it isn't.
If you're looking to get larger muscles I would recommend something with Tribbulus in it, like T-Bomb II. Almost anything else that reputes to increase testosterone is a placebo.