Iran attempted to shoot down US drone over tanker attack site in Gulf of Oman The attempt was ineffective, missing the MQ-9 by "approximately one kilometer."

Iran attempted to shoot down a U.S. drone that was surveilling the attack on one of two tankers hit in the Gulf of Oman on Thursday morning, U.S. Central Command said. The attempt missed the MQ-9 Reaper by "approximately one kilometer."

The Japanese-owned Kokuka Courageous along with another tanker, the Front Altair, were damaged by mines that the U.S. said Iran's Islamic Revolutionary Guard Corps (IRGC) had placed on the ship's hulls.

"According to our assessment, a modified Iranian SA-7 surface-to-air missile attempted to shoot down a U.S. MQ-9, at 6:45 a.m. local time, June 13, over the Gulf of Oman, to disrupt surveillance of the IRGC attack on the M/T Kokuka Courageous," CENTCOM spokesperson Lt. Col. Earl Brown said in a statement to ABC News on Saturday.

CENTCOM said that, prior to the attempt by Iran to shoot down the MQ-9, the drone had observed the Front Altair on fire.

"The SA-7 was ineffective and its closest point of approach to the MQ-9 was approximately one kilometer," Brown said. "Subsequent analysis indicates that this was a likely attempt to shoot down or otherwise disrupt the MQ-9 surveillance of the IRGC attack on the M/T Kokuka Courageous."

In the day following the attacks, Iranian small boats prevented salvage tugs from towing the Front Altair, as they had been contracted to do, a U.S. official told ABC News.

The 23 mariners on board the Front Altair were rescued shortly after Thursday's attack by the Hyundai Dubai, but Iranians aboard small boats quickly demanded the crew be turned over to their custody, a U.S. official said. The master of the Hyundai Dubai contacted the headquarters of his shipping company in Seoul and was instructed not to turn the crew over to the Iranians. However, the ship's master felt he had no choice but to comply with the Iranian demands.

After being held in Iran for two days, the crew of the Front Altair was flown to Dubai where they will continue on to their home countries, according to the Associated Press.

The Kokuka Courageous is now in territorial waters of the United Arab Emirates, a second official said.

CENTCOM also confirmed on Saturday that another U.S. MQ-9 was shot down by a Houthi SA-6 surface to air missile over Yemen on June 6.

"The altitude of the engagement indicated an improvement over previous Houthi capability, which we asses was enabled by Iranian assistance," Brown said.

ABC News' Luis Martinez contributed to this report.