The US Navy said Thursday it is doubling the number of minesweeping ships and helicopters based in the Gulf, amid growing tensions over Iran's threats to close the strategic Strait of Hormuz.

The top US Navy officer, Admiral Jonathan Greenert, told lawmakers the United States plans to send four minesweeping ships along with mine-hunting helicopters to the region -- bringing the total to eight for each type of asset.

"I wanted to be sure... that we are ready -- that our folks are proficient, they're confident and they're good at what they do in case called upon," Greenert told the Senate Armed Services Committee.

The move to boost US defenses in the region comes amid heightened tensions with Iran after it threatened to close the Strait of Hormuz, a key transit route for global oil supplies, in response to Western sanctions over Tehran's nuclear program.

The United States and Israel have said they would not accept a nuclear-armed Iran, despite Tehran's protests that its nuclear drive is for civilian purposes.

Four minesweeping ships are currently based in Bahrain, headquarters of the US Fifth Fleet. The US Navy has a total of 14 of these ships. The MH-53E Sea Dragon helicopters are equipped with sonars that can detect mines.

The US Navy also plans to improve submarine drones that can neutralize mines.

Tehran has an arsenal of about 2,000 marine mines that can be launched by a dozen of submarines or cruisers, according to experts.

In 1988, an Iranian mine damaged the USS Samuel B. Roberts frigate, causing $96 million in damage, according to the Dubai-based Institute for Near East & Gulf Military Analysis.