One of the problems with American infantry in Iraq was that there wasn't enough of it. Another problem was that the mechanized infantry (the 3rd and 4th Infantry divisions) are not as large as they were during the 1991 Gulf War. In the early 1990s, the army reduced the size of it's combat battalions (from four companies to three), and the number of combat battalions in some divisions (from 10 to 9). The net result was that, where a mech infantry division in 1991 had 232 tanks and 336 Bradley IFVs (Infantry fighting vehicles), the number is now 180 and 225. The Bradley's carry the infantry, and now there are 33 percent fewer of them. In 1991, an American mech infantry division had 24 infantry companies (about 3600 actual infantry), versus fifteen today (2700 infantry).  Moreover, the marines in Iraq noted that the army mech infantry were reluctant to leave their armored vehicles. The army light infantry, having no armored vehicles, were out and about constantly. So were the marines. This was more of a problem after the major fighting stopped, because it was easier, and more effective, to keep the peace with boots on the ground. Given a choice, mech infantry like to stay inside their vehicles.