https://www.thedrive.com/the-war-zone/28534/iran-tried-to-shoot-down-u-s-reaper-drone-near-tankers-hours-before-attacks-report

Iranian boats reportedly tried and failed to shoot down a U.S. MQ-9 Reaper drone flying, which was monitoring their movement in the Gulf of Oman just hours before attacks on a pair of oil tankers in the same general area two days ago. This comes amid separate reports that Iran has been interfering with the ongoing efforts to recover one of the two tankers, the Front Altair, which had suffered a serious fire in the incident.

CNN was first to report the new details, citing an unnamed U.S. government official, on June 14, 2019. The source described the weapon the Iranian's employed as a "missile," but did not specify what type. They added that it had missed the drone and fallen into the ocean. They did not say whether or not the unmanned aircraft had subsequently observed the Iranians conducting any actual attacks on the Front Altair or a second tanker, the Kokuka Courageous.

Given the generally small size of Iran's various armed speed boats, it seems very likely that the weapon in question was a short-range, heat-seeking, man-portable, shoulder-fired, surface-to-air missile, commonly known as MANPADS, which stands for Man Portable Air Defense System. Iran's military and quasi-military Islamic Revolutionary Guard Corps (IRGC) both have various types of these weapons in service, including locally produced clones and derivatives of Chinese models.