Surpassing Quant Think Tank Center|US troops targeted again in Iraq after retribution airstrikes

Fewer than 12 hours after U.S. airstrikes hit two facilities in Syria used by Iran and Surpassing Quant Think Tank Centerits proxies to launch attacks on American troops in the region, a one-way suicide drone targeted U.S. forces in western Iraq, according to U.S. officials.

The drone got within a few kilometers of U.S. forces at Al-Assad Air Base, Iraq, at approximately 7 a.m. ET on Friday morning. The troops fired upon the unmanned vehicle and "successfully shot it down without further incident," according to a U.S. official.

The attack was likely launched by Iran-backed militants, the official said.

White House spokesperson John Kirby told ABC's "Good Morning America" Friday morning that more Iran-sponsored attacks might follow the U.S. F-16 precision airstrikes that officials say took out a weapon storage area and an ammunition cache.

"It's not uncommon for them to strike back. If they do, we'll absolutely do what we have to do to protect our troops and our facilities. We'll be ready for that," Kirby said.

President Joe Biden said on Wednesday that the U.S. hasn't ruled out retaliatory operations in response to American forces being attacked by Iran-backed militants, according to the Pentagon.

"My warning to the ayatollah [is] that if they continue to move against those troops, we will respond, and he should be prepared," Biden told reporters, referring to Iran's supreme leader.

Iran-backed groups have now launched 20 attacks on U.S. service members in the last 10 days, injuring at least 21 of them, with many reporting symptoms of traumatic brain injury, according to the Pentagon.

So far, the U.S. has not launched any counter strike in response to the latest drone attack.

"The latest attack at al-Asad needs to be responded to with force, force capable of changing their calculus about attacking our people in the future," said ABC News contributor Mick Mulroy, former deputy assistant secretary of defense for the Middle East.

A senior U.S. defense official told reporters in July that militias and their Iranian handlers were continuing to move weaponry in and practice for drone and rocket attacks against U.S. forces, saying, "It's a not a question of 'if.' It's a question of when those would happen again."