The U.S. Army has created a portable "kill house" (Live Fire Virtual Targeting, or LFVT system), which is currently being used by the U.S. 173rd Airborne Brigade in Italy. A kill house is one in which you can use live ammo while carrying out combat training inside buildings. These days, it's more commonly called an "assault house" or "shoot house." But during World War II, when the concept was invented, they were called "kill house," and many troops still use that more descriptive, if less PC, term. What's really remarkable about the army's new LFVT is that it's mainly for training infantry. Back during World War II, kill houses were developed to train commandos. You couldn't trust anyone but commandos to use live ammo, in close quarters, during training.
Training standards for American infantry have gone up quite a lot in the last two decades. The troops are now expert enough to train regularly with live ammunition. Part of this is due to the introduction of MILES (think laser tag) gear two decades ago. With MILES, the infantry learned how to use their weapons without shooting each other. In all earlier wars, you didn't want to be near green troops in their first battle. Such inexperienced troops tended to fire haphazardly, often hitting each other. MILES cured infantry of that habit, without using real ammo. The value of MILES was seen in the 1991 Gulf War, and that led to more training with live ammunition.
The most difficult type of training is for combat indoors. "Clearing buildings" is dangerous, chaotic and hard on the nerves. Again, very deadly for green troops. Commandos developed the "kill house" concept to provide realistic experience for that sort of thing, as even elite troops needed practice. If was soon found that this experience provided a decisive edge when facing troops without such training, or experience in fighting in buildings. When fighting indoors, everyone is unsure of who is where and up to what. Whoever moves the most decisively, and shoots the straightest, tends to win fast, and with little loss.
Kill houses can be used firing blanks, but that does not give the same training effect. Another option is using "simunition." This is special, lower velocity, ammo that will leave a welt, but not cause a serious wound if you get hit. Even commandos sometimes use simunition, but this requires special parts for their weapons and, of course, the special ammunition. Much better to use the real thing.
The portable LFVT uses computer generated, photorealistic images of rooms and people (both hostile and not) inside them. This is based on the training simulations developed from the "America's Army". This online game was originally developed to assist training, but was so realistic that it was modified for training troops as well. Like "America's Army," LFVT used a lot of technology taken from what is used to make movies and video games.
The portable LFVT used by the 173rd is the fourth one built. The other three are permanent, and troops can use regular ammunition. These have walls with two inches of wood, backed by steel thick enough to stop 5.56mm bullets. One thing that is still difficult to train for is the problem of shooting through walls and ceilings. Sometimes you do this to get at the enemy, but at other times, you accidentally get at your own buddies. So, there's always something to learn once you start doing the real thing. The 173rd troops use simunition, which does not penetrate walls.
The video game version allows troops to work with their tactics, and shooting through walls and ceilings. But the full size shoot houses are as realistic as possible, close to the real thing so that the troops will have some experience when they face an enemy shooting back with real bullets.
The permanent LFVTs cost about a million dollars, while the portable one costs about $250,000. The other three permanent ones are in the United States, with a fifty LFVT being built at West Point (the U.S. Army Military Academy).