During a news briefing on Friday, John Kirby accused Iran of “harassing, attacking or interfering” with the navigational rights of 15 internationally-flagged commercial vessels over the past two years.
“Today, the Department of Defense will be making a series of moves to bolster our defensive posture in the Arabian Gulf,” the White House spokesman told reporters.
It remains unclear what additional assets the US military will move to the region.
“We have seen repeated Iranian threats, armed seizures and attacks against commercial shippers who are exercising their navigational rights and freedoms in international waterways,” Kirby added.
Iran has recently seized two oil vessels, including one headed to the US, in late April and early May.
Iranian officials have stated one of the tankers collided with an Iranian vessel and tried to flee, while the other was taken into Iranian territorial waters as the result of a judicial order following a legal complaint.
Iranian military officials have warned that any threat against the Iranian ships by the US or its allies will receive a harsh and regrettable response.