John Kirby, a spokesman for the White House, said on Friday that the Pentagon will strengthen its defensive posture in the Gulf region because Iran has increased its attacks on commercial shipping in recent months.

In the past two years, Iran has “harassed, attacked, or interfered with the navigational rights” of fifteen commercial vessels flying an international flag, according to Kirby.

“Today, the Department of Defence will take several steps to strengthen our defensive posture in the Gulf,” Kirby told reporters during a briefing.

US Central Command will provide details in the following days, according to Kirby.

The move comes after Iran detained a second oil tanker within a week in Gulf waters earlier this month, prompting the State Department to call for the vessel’s release, the latest in a series of actions against commercial vessels in Gulf waters since 2019.

The US Navy’s Bahrain-based Fifth Fleet reported on May 3 that the Iranian Islamic Revolutionary Guard Corps Navy seized the Panamanian-flagged oil tanker Niovi as it passed through the Strait of Hormuz.

The incident occurred days after Iran commandeered an oil tanker flying the flag of the Marshall Islands in the Gulf of Oman.

Kirby stated that the United States vehemently condemns actions that threaten and impede commercial shipping and will not permit foreign powers to endanger the navigation of Middle Eastern waterways.

“We have seen repeated Iranian threats, armed seizures, and attacks against commercial shippers who are exercising their navigational rights and freedoms on international waterways,” he said.

According to data from analytics firm Vortexex, roughly one-fifth of the world’s crude oil and oil products transit through the Strait of Hormuz, a choke point between Iran and Oman.