On the theory that every little bit counts, the U.S. Space Command, which controls the 28 satellites that make up the GPS system, tweaked the birds to increase accuracy during the Iraq campaign. Normally, the GPS system provides 10 foot accuracy. But if the satellites have their position data updated as they moved over Iraq, you can get accuracy to under eight feet (in this case, 7.3 feet). The satellites normally suffer a bit of drift, and atmospheric conditions beneath the birds is ever changing (and having an effect on the GPS signal being sent to the ground.) To correct this, the ground controllers periodically update data in the satellites. Doing this updating more frequently will make the GPS signal more accurate. Normally, making the GPS signal more accurate has no practical effect. But when GPS is being used to guide a lot of smart bombs, that little bit of additional accuracy can be useful. This technique is called GPS Enhanced Theater Support and was first developed three years ago.