Is this the incident that will make tensions between Washington and Tehran boil over after months of increasing acrimony? A U.S. official has confirmed Iranian state news reports that Iran shot down a U.S. military drone Thursday in a fresh escalation in the standoff. Earlier, Iran said it downed a Global Hawk drone when it entered Iranian airspace. However, the U.S. official told ABC News that it was an unarmed and unmanned U.S. Navy MQ-4C Triton drone and that it was flying over international airspace, not Iranian. It’s a direct attack on a U.S. military asset and could trigger a serious response from the U.S. in the days to come.