Israeli defense officials say that Palestinian militants in the Gaza Strip have for the first time fired an antiaircraft missile at Israeli aircraft. The officials say the militants fired a Strela shoulder-fired missile at an Israeli helicopter operating over Gaza last week but missed their target. The officials said Israeli intelligence has long believed that militants in Gaza possessed these weapons, but this was the first time they were fired. They said the air force had taken special precautions for several years assuming that the threat existed. Israel believes that the weapons originated in Libya and were smuggled through tunnels along the Egyptian border. Palestinian militant groups have never acknowledged possessing the weapons.