It is unclear if the new forces will deploy from American bases in the Middle East or from the United States. There are roughly 500 American troops in Saudi Arabia, part of a 2,000-strong contingent that was dispatched to the region after a rash of attacks on oil tankers in the Gulf of Oman and the shooting down this summer of an American drone by an Iranian surface-to-air missile over the Strait of Hormuz. The loss of the drone nearly led to an American airstrike on Iran, but Mr. Trump called it off at the last minute.

The new deployment includes one Patriot missile battery, a surface-to-air holdover from the Cold War that is currently also used by the Saudi military. The other equipment includes four advanced Sentinel radars that can track drones and cruise missiles. On Thursday, Lockheed Martin, the producer of the Sentinel, won a potential $281 million contract to supply the Army with 18 of the radars.

In the statement, Mr. Hoffman said the deployment to Saudi Arabia would “augment the kingdom’s air and missile defense of critical military and civilian infrastructure.” The Pentagon also hopes that some European nations — like Britain, France and Germany — will contribute forces to the kingdom to further deter Iran. The three countries blamed Iran for the attacks in a joint statement Monday.

The statement added that the defense secretary, Mark T. Esper, had also placed two additional Patriot batteries, and a more advanced surface-to-air missile system, on standby in case they were needed for additional defenses in the country.

Last week, Mr. Trump announced a new round of sanctions against Iran’s national bank. The administration is also considering other nonmilitary options against Iran, including cyberattacks on the country’s infrastructure.