Iran is firing fewer missiles at Israel each day, making it easier for Israeli air-defense systems to intercept them, according to Israeli officials and air-defense experts.

Israel may succeed in taking out Iran’s air defenses, ballistic missiles and much of its nuclear program. But that would still leave hundreds of thousands in the military, the Revolutionary Guard and forces known as the Basij, who played a key role in quashing waves of anti-government protests in recent years.