US responds to Iran threats to close strategic Persian Gulf waterway

The US military has attempted to diffuse concerns a major waterway would be closed after Iran's threats to jeopardise regional oil exports.

Captain Bill Urban, a spokesman for the US military's Central Command, told The Associated Press on Wednesday that American sailors and its regional allies "stand ready to ensure the freedom of navigation and the free flow of commerce wherever international law allows".

On Tuesday, Iranian President Hassan Rouhani suggested Iran could halt regional exports if it is stopped from exporting oil after America pulled out of the nuclear deal with world powers.

Rouhani didn't elaborate on the comments, but when pressured in the past, Iran has threatened to close the strategic Strait of Hormuz through which one third of the world's oil supply passes.

Iran is OPEC's second-largest crude exporter with more than two million barrels a day.

After the US pulled out of the nuclear deal with Iran, Washington has been pushing allies to stop oil imports from Iran altogether by November.

The US State Department said on Monday that it remains determined to force Iran to change its behaviour by cutting its oil exports "to zero".

Brian Hook, the senior official leading negotiations with US allies on a new Iran strategy, said Washington is confident the world has enough spare oil capacity to replace Iranian crude.

Meanwhile, Iranian General Qassem Soleimani reportedly sent a letter to Rouhani applauding his stance.

Soleimani, the head of the Revolutionary Guard's expeditionary Quds Force, said his forces were "ready for any policy".