Iranian lawmakers recently put forward a measure that would choke off the oil-shipping lanes through the Strait of Hormuz, the conduit for about 20 percent of globally traded crude oil. The move was seen as a response to U.S. and European sanctions targeting Iran's energy sector.
U.S. officials said the Navy sent the SeaFox submersible to the region to search for and destroy mines in the Persian Gulf, the Los Angeles Times reports. Marine Gen. James Mattis, the top U.S. military commander in the Middle East, issued an urgent order for the submersible in May.
The Times reports authorities in the United States are worried Iran may respond to sanctions by targeting oil installations in the Persian Gulf apart from the move on the Strait of Hormuz.
Iran recently conducted a series of military drills it said targeted simulated enemy installations.
Iran, as of 2010, was ranked No. 3 in terms of crude oil reserves among members of the Organization of Petroleum Exporting Countries. The U.S. Energy Department's Energy Information Administration this week reported Iranian crude oil production has declined steadily since the end of 2011, however.