Syria and Iraq say civilians were among those killed in the strikes.

The aftermath of the U.S. military strikes targeting sites in Syria and Iraq began coming into focus on Saturday morning as a Britain-based Syria monitoring group said that at least 18 members of an Iran-backed group had been killed in strikes there and the Iraqi government said that 16 people had been killed, including civilians.

The Biden administration warned that the strikes overnight on sites used by Iranian forces and Iran-backed militias in retaliation for the killing of three U.S. troops last week would not be the last.

Civilians, as well as soldiers, were among those killed in Syria, the country’s defense ministry said. At least 18 members of Iran-backed groups were killed in strikes on 26 sites there, according to the Syrian Observatory for Human Rights, a Britain-based monitoring group that has researchers in Syria.

The Iraqi government said in a statement on Saturday that the strikes had killed 16 people, including civilians, and wounded 25 more.

American officials said they were confident that the strikes, on 85 targets at seven sites in the two countries, had hit “exactly what they meant to hit,” but said that analysts would make a closer assessment in daylight.

American officials also said the targets were all linked to specific attacks against U.S. troops in the region, describing them as command and control operations, intelligence centers, weapons facilities and bunkers used by Iran’s Islamic Revolutionary Guards Corps Quds Force and affiliated militia groups.

“Our response began today,” President Biden said in a statement shortly after witnessing the return of the bodies of the U.S. soldiers who were killed at a military outpost in Jordan last week.

Friday’s strikes did not hit any targets inside Iran. Both Washington and Tehran have made it clear in recent days that they do not want a direct conflict.

Brig. Gen. Yahya Rasool, a spokesman for Iraq’s military, issued a statement calling the strikes on Iraq “unacceptable” and a violation of the country’s sovereignty, warning that the escalation “will drag Iraq and the region into unforeseen consequences.” John F. Kirby, a U.S. National Security Council spokesman, said the Iraqi government had been notified ahead of the strikes.

The strikes used more than 125 precision-guided munitions, according to a statement by United States Central Command. The strikes took 30 minutes, officials said, and were largely conducted by two American B-1B bombers, which departed from Dyess Air Force Base in Texas early Friday for a more than 6,000-mile flight. Using U.S.-based bombers allowed commanders in the region to keep their land- and carrier-based strike aircraft in reserve for follow-up strikes, one official said.

Since the Oct. 7 start of the Israel-Hamas war, which has devastated Gaza and inflamed the Middle East, Iran and its allied militias have launched more than 160 attacks on U.S. troops in the region and have struck at commercial ships in the Red Sea.