TEHRAN, Iran (AP) — Iran’s Revolutionary Guard shot down a U.S. surveillance drone on Thursday amid heightened tensions between Tehran and Washington over the collapsing nuclear deal with world powers, American and Iranian officials said, though they disputed the circumstances of the incident. The Guard said it shot down the RQ-4 Global Hawk drone over Iranian airspace, while the U.S. said the downing happened over international airspace in the Strait of Hormuz. The different accounts could not be immediately reconciled. The U.S. military’s Central Command called it an “unprovoked attack” and President Donald Trump tweeted that “Iran made a very big mistake” in shooting it down. Previously, the U.S. military alleged that Iran had fired a missile at another drone last week that was responding to the attack on two oil tankers near the Gulf of Oman. The U.S. blames Iran for the attack on the ships; Tehran denies it was involved.