One way to reduce coalition casualties has been to build large bases with everything thing people working there need. The largest example of this is in Baghdad, where a four square mile section of the city is surrounded by a fifteen foot high wall and armed guards. Many of the American (and other) soldiers and civilians inside this "Green Zone" never leave it except when they arrive from, and leave for, the airport. Saddam made it easy to create Green Zones by building his build palace compounds and closing off areas for the exclusive use of his followers. However, the combat troops often operate out of hundreds of smaller bases and "safe houses" (which are often temporary.)