EL-ARISH, Egypt — Egyptian military attack helicopters fired missiles on suspected Islamic militants in the Sinai Peninsula on Wednesday, officials and residents said, in the first Egyptian airstrike in the territory since 1973 in the wake of the bloodiest ever militant attacks on the army.

The use of air power marked a sharp escalation in Egypt's fight against Islamic militants who have become increasingly active in the mountainous, desert peninsula bordering Israel. Earlier this week, militants stunned the Egyptian army with a bold, surprise attack in which gunmen killed 16 soldiers, stole armored vehicles and drove into Israel to attempt another attack.

In a statement read out on state TV, the military said it has started a joint military-police ground operation in Sinai, backed by warplanes, to "restore stability and regain control" of the Sinai. It provided little detail.