One of the problems with training American soldiers for urban warfare is the large number of SWAT (Special Weapons And Tactics) teams maintained by police departments. SWAT teams are trained to deal with armed and hostile people inside buildings, often with hostages involved. SWAT teams have developed tactics and techniques over the years, based on their experience. Often, SWAT techniques will be adopted by the military. This is often a mistake. SWAT teams almost always deal with armed people in one place, and have lots of other police to clear the area so the SWAT team members can do their job without worrying about stray civilians. More important, SWAT teams usually know exactly where this single threat is and their tactics are optimized to deal with this while minimizing losses to the SWAT team. The military faces a very different situation. In wartime, an urban battlefield has numerous armed hostiles and you never know where they all are. A classic example of excellent SWAT tactics that won't work in wartime is the way a SWAT team will bunch up outside a door they are about to go through to get an armed suspect. In wartime, you should never bunch up, as this makes you liable to get hit by one blast of enemy fire, or an enemy grenade. Military street fighting features much faster and more intense action than your average SWAT team engagement. As the Department of Defense intensifies it's study of urban warfare, more of these bad borrowings from the SWAT community are coming to light.