The U.S. military will place additional air defense systems in Saudi Arabia, the Pentagon said Thursday, in the Trump administration’s first known military response to what it says was a brazen Iranian assault on the kingdom’s oil industry.

Defense Secretary Mark T. Esper’s decision to authorize the deployment of an additional battery of Patriot missiles and four Sentinel radar systems, accompanied by 200 American troops, to shore up a key ally is a modest step that represents the administration’s desire, at least for now, to avoid additional escalation in U.S.-Iranian tensions.

The administration has maintained that Iran launched a complex attack involving drones and missiles against two important Saudi oil sites Sept. 14. Officials say they have compiled a convincing intelligence dossier on the assault but have not released details.

Iran has repeatedly denied involvement, pointing instead to a claim of responsibility by Yemen’s Houthi rebels, who have fired thousands of missiles and artillery pieces in their war with neighboring Saudi Arabia.

Pentagon spokesman Jonathan Hoffman said the deployment would “augment the kingdom’s air and missile defense of critical military and civilian infrastructure.”

“These steps are a demonstration of our commitment to regional partners, and the security and stability in the Middle East,” he said in a statement.

Hoffman said Esper also put additional U.S. forces on a “prepare to deploy” status, meaning that two more Patriot batteries, along with a different missile defense system called the Terminal High Altitude Area Defense system, could be sent in short order.

Thomas Karako, a missile defense expert at the Center for Strategic and International Studies, characterized the move as more symbolic than militarily significant.

“This kind of deployment is a political statement,” he said. “It communicates that we’re there with our partners.”

The Pentagon declined to address whether it was considering additional steps, such as extending the deployment of the aircraft carrier USS Abraham Lincoln and its accompanying ships or dispatching additional surveillance aircraft to the region.

The United States has more than 60,000 U.S. troops deployed across the Middle East and South Asia in what it calls the U.S. Central Command region.

The attack on facilities belonging to Saudi oil firm Aramco, which U.S. officials saw as particularly provocative given the kingdom’s role in global oil supply, was the latest in a long series of moves heightening tensions between Washington and Tehran.

President Trump has described Iran as a significant U.S. rival, pulled out of the nuclear deal struck by his predecessor and authorized a campaign of sanctions that has constricted the Iranian economy.

But especially since the departure of national security adviser John Bolton, a well-known Iran hawk, Trump has pointed to his desire to avoid war with Iran, a conflict that military leaders have warned would be unpredictable.

The deployment will add to Saudi Arabia’s suite of Patriots, which U.S. officials say number about two dozen.

Those systems can attempt to shoot down cruise and ballistic missiles but have a fixed radar scope and have been mostly oriented south toward Yemen rather than east toward Iran, Karako said. The Sentinel radar systems, meanwhile, have a 360-degree radar capability, allowing them to detect attacks from multiple directions.

Earlier this week, Trump hinted the United States may be taking other, potentially covert, steps against Iran.

“Let me just put it this way: A lot of things are happening with respect to Iran, a lot more than you would know, a lot more than the media knows,” he said, speaking during a visit to New York for the U.N. General Assembly.

Earlier this summer, the United States conducted a cyberattack against Iran’s Revolutionary Guard Corps following an incident in which Iranian forces downed an American drone.

Also speaking in New York, Iranian President Hassan Rouhani told reporters on Thursday that Iran had nothing to do with the missile attack on Aramco facilities in Saudi Arabia and demanded proof of the country’s alleged involvement.

“I ask, where is your evidence?” he said, through an interpreter.

In an implicit rebuke to the United States, he also called for those who have supplied weapons to Saudi Arabia and the United Arab Emirates, which are jointly battling the Houthis in Yemen, to halt the arms sales and press for a peace settlement. The Gulf countries’ coalition has come under widespread criticism for repeatedly striking civilian sites in Yemen.

Rouhani repeated his demand that the United States lift sanctions before Iran would agree to negotiations.

“If the time comes when they are taken off the table, of course the possibility exists to talk to America,” he said.

The Iranian president said Iran would be open to taking steps “above and beyond” the 2015 nuclear talks Trump abandoned, but only if the United States returns to its commitments under the deal. But he said Iran would not discuss ending its missile activity until the United States and Europe stop arms sales to the region.

The administration has also sought assistance from other countries, particularly in Europe and the Middle East, to counter what it depicts as increasingly dangerous Iranian actions. In the wake of the drone incident in June, the United States launched a partnered operation to enhance vigilance against Iranian attacks at sea.

In his statement, Hoffman placed the onus on U.S. allies to “contribute assets” to Saudi Arabia’s defense. Gen. Joseph F. Dunford Jr., chairman of the Joint Chiefs of Staff, spoke with his British counterpart on Thursday.

Carol Morello in New York contributed to this report.