US diplomats and troops in Iraq and Syria have been targeted in three rocket and drone attacks in the last 24 hours, according to US and Iraqi officials, including at least 14 rockets hitting an Iraqi air base hosting US forces, injuring two US service members.

While there were no immediate claims of responsibility for the attacks, which were part of a wave targeting US troops or bases in Iraq and Syria, analysts believed they were part of an Iranian-backed militia campaign.

After US strikes on the Iraqi-Syrian border killed four of their members last month, Iraqi militia groups aligned with Iran vowed retaliation. According to coalition spokesman US Army Colonel Wayne Marotto, two people were slightly injured in the rocket attack on the Ain al-Asad air base in western Iraq. The rockets landed on the base and its surroundings. He had previously stated that three people had been injured.

According to US officials who spoke on the condition of anonymity, the two injured personnel were US service members. One had a concussion, and the other had minor cuts, according to one of the officials.

According to Iraqi security sources, two rockets were fired at the US Embassy in Baghdad’s Green Zone early Thursday. One of the rockets was diverted by the embassy’s anti-rocket system, according to one of the sources, a security official whose office is inside the Green Zone. According to security officials, the second rocket landed near the zone’s perimeter.

According to the sources, sirens could be heard from the embassy compound inside the zone, which houses government buildings and foreign missions.

In Syria, the US-backed Syrian Democratic Forces said a drone attack on the Al Omar oil field in an eastern area bordering Iraq, where US forces came under rocket fire but escaped unharmed on June 28, did not cause any damage. According to the Pentagon, a drone was shot down in eastern Syria, but no US service members were injured and no damage was done.

According to Iraqi army officials, the pace of recent rocket and explosive-laden drone attacks on bases hosting US forces has been unprecedented.

According to Iraqi military sources, a rocket launcher mounted on the back of a truck was used in Wednesday’s attack and was discovered on nearby farmland that had been set ablaze.

According to Kurdish security sources, a drone attacked Erbil airport in northern Iraq on Tuesday, targeting a US base on the airport grounds.

On Monday, three rockets landed on Ain al-Asad, causing no casualties. The US has been holding indirect talks with Iran in order to bring both countries back into compliance with the 2015 Iran nuclear deal, which then-President Donald Trump reneged on. No date has been set for the next round of talks, which were called off on June 20.

The attacks, according to Hamdi Malik, an associate fellow at the Washington Institute and an expert on Iraq’s Shi’ite militias, were part of a coordinated escalation by Iranian-backed militias in Iraq.

The attempt to strike in eastern Syria appeared to be the first instance of operations being carried out in both countries at the same time. “Iran appears to have given them the go-ahead to escalate, especially given the state of the nuclear talks. At the same time, they do not want to escalate beyond a certain point – they are more vulnerable to US air strikes than they were previously – and they do not want to complicate Iran’s negotiations with the West.”

Last week, the United States informed the United Nations Security Council that it had conducted air strikes against Iranian-backed militias in Syria and Iraq in order to deter them and Tehran from carrying out or supporting further attacks on US personnel or facilities.

Iran denied supporting attacks on U.S. forces in Iraq and Syria and condemned U.S. air strikes on Iranian-backed groups.