WASHINGTON (Reuters) - Acting U.S. Defense Secretary Patrick Shanahan has approved a new deployment of Patriot missiles to the Middle East, a U.S. official told Reuters on Friday, in the latest U.S. response to what Washington sees as a growing threat from Iran.

FILE PHOTO: Acting U.S. Defense Secretary Patrick Shanahan testifies before a House Appropriations Defense Subcommittee hearing on the Department of Defense - FY2020 Budget request on Capitol Hill in Washington, U.S., May 1, 2019. REUTERS/Yuri Gripas/File Photo

The decision further bolsters U.S. defenses and comes after the Trump administration expedited the deployment of a carrier strike group and sent bombers to the Middle East following what it said were troubling indications of possible preparations for an attack by Iran.

The U.S. official, who spoke on condition of anonymity, declined to say how many Patriot batteries would be deployed. The Patriot missile defense system is made by Raytheon Co. and is designed to intercept incoming missiles.

The decision to send Patriot missiles to the region would mark a reversal of sorts, coming just months after the Pentagon removed several Patriot batteries from the Middle East.

Last year, officials described the withdrawal of the Patriots as part of a broader effort to adjust U.S. military deployments globally, as the Pentagon sought to prioritize military challenges from Russia and China.

RISING TENSIONS

Tensions between Iran and the United States have escalated sharply in recent weeks.

The United States has effectively ordered countries worldwide to stop buying Iranian oil or face U.S. sanctions, which Washington says are aimed at completely choking off Iranian crude exports.

Washington last month blacklisted Iran’s Revolutionary Guard as a terrorist group.

U.S. officials say they have detected troubling indications that Iran could be preparing a military response.

U.S. officials, speaking on condition of anonymity, say one of the pieces of intelligence indicated Iran had moved missiles on boats. One of the officials said the particular missile observed was perhaps capable of launching from a small ship.

The officials also noted growing concerns about the threat from Iran-backed Shi’ite militia in Iraq, which have long avoided any confrontation with U.S. troops under the shared goal of defeating Islamic State, a Sunni militant organization.

In an advisory posted on Thursday, the U.S. Maritime Administration (MARAD) said that since early May there had been an increased possibility of Iran or its regional proxies taking action against U.S. and partner interests.