New Delhi, June 16 -- The United States military has overseen scores of secretive ship-to-ship oil transfers to keep Gulf energy exports flowing, using aerial and water drones as well as helicopters in an operation to guide convoys to awaiting tankers.

The operation on the edge of the Strait of Hormuz employs a shuttling technique long used by Iran to skirt sanctions. Two specific locations where the oil transfers take place were identified by 11 people familiar with the operation - one off the coast of Fujairah in the United Arab Emirates and the other off Oman's port of Sohar. It started in early May, and at least 92 ships have been involved in the transfers, according to shipping data and satellite imagery reviewed by Reuters.

As rec...