Throughout the 1990s, the U.S. air force moved towards a new style of bombing. Obsessed with avoiding losses to ground fire, bombing was done from 15,000 feet. This kept aircraft out of range of anti-aircraft guns and portable heat seeking missiles. Longer range missiles were avoided using extensive electronic warfare efforts. But there was one major problem that no improvements in guided bombs and sensors could overcome; you had a hard time hitting anything from that far up. Moreover, operating that high made it easier for the enemy on the ground to use deception. This was seen with embarrassing effect when NATO ground troops moved into Kosovo in 1999 and found only a handful of destroyed armored vehicles. The NATO air forces had claimed hundreds of vehicles destroyed. Many air force officers now admit there is a problem and are looking hard at solutions. The most painful solution is to depend on countermeasures for portable and low altitude missiles. Aircraft would then be able to go in low and hit real targets, not decoys. Other solutions include better high altitude sensors, but so far this approach has consistently failed.