Israel is running low on defensive Arrow interceptors, according to a U.S. official, raising concern about the country’s ability to counter long-range ballistic missiles from Iran if the conflict isn’t resolved soon. The U.S. has been aware of the capacity problems for months, the official said, and Washington has been augmenting Israel’s defenses with systems on the ground, at sea and in the air. Since the conflict escalated in June, the Pentagon has sent more missile defense assets...