So far this year, the U.S. Navy has expelled a dozen midshipmen (cadets from the Naval Academy) for using legal recreational drugs. It's not just the cadets who are getting caught. In February, 16 sailors got the boot from the military, for using or selling synthetic drugs, in this case a marijuana-like item called "Spice." The sailors were assigned to an amphibious carrier (USS Bataan). Currently, 30-40 sailors a month are caught using synthetic drugs. This includes midshipmen at the Naval Academy who were expelled. They are all in the navy, until the navy finds out you are using spice.
For the last two years, the U.S. Department of Defense has been cracking down on troops using recreational drugs that are not yet illegal. There is also a crackdown on the use of drugs that mask use of illegal drugs. Because of both these trends, the random urine tests no longer work as well as they used to.
Over the last few years, an increasing number of test defeating products have appeared on the market. The navy has responded by prohibiting sailors from possessing any of these items. If this doesn't reduce the cheating sufficiently, the navy may have to go to hair tests. Drug traces remain in hair for about 90 days, but it is more time consuming and expensive to test hair. There are also products (like special shampoos) that will reduce the effectiveness of the hair test. But the current products used to mask the urine tests are not a hundred percent effective, so people are still getting caught, and the military is making more of an effort to identify and punish dealers and distributors of these drugs, especially in ship crews.
All this moved into high gear several years ago when the military realized that anyone caught using any substance that causes intoxication, had to be expelled or punished. These transgressions can range from sniffing glue (another legal substance) to the many organic substances and designer drugs on the market, that are not yet illegal (like Spice), and may never be. The fear is that widespread use of these substances could lead to death or injury. Troops frequently handle dangerous equipment, or are responsible for maintaining weapons and vehicles (like helicopters or jets) which are very vulnerable to errors by the maintainers.
But sometimes troops are allowed to use drugs to fight fatigue. For over a century, the solution has been amphetamines ("speed"). However, this drug can impair judgment, making the user more aggressive, for example. In the last decade, kinder and gentler medications have become available. With some of these, tests showed that user performance was degraded 15-30 percent, versus 60-100 percent for those who took nothing at all after 24 hours of being awake. While these new drugs did a pretty good job, the current dextroamphetamine was still a bit better. So amphetamines remain competitive.
Wakefulness can be a potent weapon, especially for commandos, or troops engaged in prolonged combat (like the Battle of Fallujah in 2004). Without these wakefulness drugs, you would have to either pull troops out of action so they could rest, or leave them in and risk having them make fatal mistakes. Either way, you have a problem, because there are never enough troops to get the job done. But with the wakefulness medications, you can solve the problem, for a few days, anyway. Prolonged use of these drugs is not healthy. But neither is being drowsy during combat.
Islamic terrorists and the Taliban are, in theory, anti-drug, but they tolerate the use of narcotics among their fighters, as this often makes it possible for young, untrained gunmen to make audacious attacks. Drug tests on the bodies often reveals the presence of mood enhancing drugs, often large doses of methamphetamine (enough to make you fearless, not just more alert.)