U.S. troops are increasingly using an herbal mix called "Spice" that mimics a marijuana high and can bring on hallucinations that last for days.
Alarmed military officials have launched an aggressive testing program that this year has led to the investigation of more than 1,100 suspected users.
So-called "synthetic" pot, which is legal to purchase in stores as a herbal incense, has become popular nationwide in recent years. Marijuana-specific drug tests typically can't trace it, but urine tests can detect it.
Spice can have dangerous side effects, as ingredients can often vary.
Two years ago, only 29 Marines and sailors were investigated for Spice. This year, the number topped 700. Those found guilty of using Spice are kicked out.
The Air Force has punished 497 airmen, compared to last year's 380.
Early in 2011, 25 Air Force Academy cadets were investigated for abusing the substance.
“The abuse of these products by military members, cadets and cadet candidates contradicts the nature of the profession of arms, threatens our military readiness and impairs our responsibilities to the Air Force and our nation,” Lt. Gen. Mike Gould, USAFA Superintendent, said at the time.
The Army does not track Spice investigations but says it has medically treated 119 soldiers.
Military officials emphasize none was believed to be high while on duty.