The Pentagon has decided to leave a sophisticated missile defense system in Jordan after it is used in a training exercise there, officials said Monday, a move that could position the U.S. military to play a more assertive role in the outcome of Syria’s civil war.

Officials said Defense Secretary Chuck Hagel approved the proposal to leave the Patriot batteries in Jordan, a U.S. ally that shares a border with Syria and has been flooded with Syrian refugees fleeing the carnage. The U.S. military has also deployed personnel to Jordan to assess military options and help the kingdom coordinate humanitarian efforts.

Patriot batteries, which were deployed along the Turkish border this year, could be used to establish a no-fly zone in Syria. The Obama administration has been reluctant to intervene militarily in the civil war, but several U.S. lawmakers are pressing for Washington to play a more assertive role.

Oscar Seara, a spokesman for U.S. Central Command, said the military would be deploying Patriot missile launchers and F-16 fighter planes as part of a training exercise with the Jordanian military called Eager Lion.

“In order to enhance the defensive posture and capacity of Jordan, some of these assets may remain beyond the exercise at the request of the government of Jordan,” Seara said.

A senior defense official said Hagel, who is on an overseas trip, signed off on the Patriot proposal over the weekend. The decision was first reported by CNN.

Patriot batteries were built to intercept Scud missiles, a type of long-range weapon the Syrian government has used to target rebel strongholds. Although there is no sign Damascus intends to attack its neighbors, analysts have said the deployment of the batteries in neighboring countries sends a powerful message of support from the West.

They probably also convey to President Bashar al-Assad that the international community is logistically positioned to enforce a no-fly zone if Washington and its allies were to agree on that approach to tilt the scales in the favor of rebels.

Sen. John McCain (R-Ariz.), one of the U.S. lawmakers who has pressed the Obama administration to play a more forceful role in Syria, told the Jordan Times during a recent visit to the kingdom that the deployment of Patriot batteries could be a “first step” to carve out a buffer zone in which rebels and civilians could operate without fear of aerial attacks.

Jordanian officials have said the system would be used only for defensive purposes, to shield the country from missiles that could be fired across its border intentionally or by mistake.