US fighter jets launched airstrikes early Friday on two locations in eastern Syria linked to Iran’s Revolutionary Guard Corps, the Pentagon said, in retaliation for a slew of drone and missile attacks against US bases and personnel in the region that began early last week, via the Associated Press.

The US strikes reflect the Biden administration’s determination to maintain a delicate balance. The US wants to hit Iranian-backed groups suspected of targeting the US as strongly as possible to deter future aggression, possibly fueled by Israel’s war against Hamas, while also working to avoid inflaming the region and provoking a wider conflict.

According to a senior US military official, the precision strikes were carried out near Boukamal by two F-16 fighter jets, and they struck weapons and ammunition storage areas that were connected to the IRGC. The official said there had been Iranian-aligned militia and IRGC personnel on the base and no civilians, but the US does not have any information yet on casualties or an assessment of damage. The official would not say how many munitions were launched by the F-16s.

A senior defense official said the sites were chosen because the IRGC stores the types of munitions there that were used in the strikes against US bases and troops. The two officials briefed reporters after the strikes on condition of anonymity to provide details on the mission that had not yet been made public.

According to the Pentagon, there have now been at least 19 attacks on US bases and personnel in Iraq and Syria since Oct. 17, including three new ones Thursday. Air Force Brig. Gen. Pat Ryder said 21 US personnel were injured in two of those assaults that used drones to target al-Asad Airbase in Iraq and al-Tanf Garrison in Syria.

In a statement, Defense Secretary Lloyd Austin said the “precision self-defense strikes are a response to a series of ongoing and mostly unsuccessful attacks against US personnel in Iraq and Syria by Iranian-backed militia groups that began on October 17.”

He said President Joe Biden directed the narrowly tailored strikes “to make clear that the United States will not tolerate such attacks and will defend itself, its personnel, and its interests.” And he added that the operation was separate and distinct from Israel’s war against Hamas.

The senior defense official told reporters that the F-16 airstrikes will have a significant impact on the ability of Iranian proxy groups to continue to attack US forces. Asked what groups were targeted, the official said there are several that can have different names, but the US holds Tehran responsible for funding, arming, equipping and directing the proxies. The official said the airstrikes were not designed to expand the conflict in the region, but to compel Iran to direct the militia groups to cease the attacks on American bases and personnel.