Two US military service members were “physically attacked” in the port city of Izmir in western Turkey on Monday by members of an anti-American youth group, authorities said.

Fifteen suspected assailants were detained in the attack on the two service members, who were dressed in civilian clothing at the time of the incident. Five other US service members joined in the incident after seeing the violent encounter, officials said.

Those detained were members of the Turkey Youth Union (TGB), a youth offshoot of the nationalist opposition Vatan Party. Police intervened in the incident and authorities are conducting an investigation, officials said.

“We can confirm reports that US service members embarked aboard the USS Wasp were the victims of an assault in İzmir today, and are now safe,” the US embassy to Turkey said on X. “We thank Turkish authorities for their rapid response and ongoing investigation.”

An apparent TGB social media account posted a video on X that purported to show a group of men holding a US soldier and placing a white hood over his head.

“No one will be able to respond to the cries for help from U.S. soldiers. Your hands are stained with the blood of our brave soldiers and thousands of Palestinians,” @YouthUnionTR said in its X missive.

TGB posted a video on X in November 2021 where members boasted about putting a sack on a US soldier. “YANKEE GO HOME!” TGB said in a caption on the post.

The US embassy in Ankara said earlier Monday that the Wasp was on a port visit to Izmir, a coastal town. The ship arrived on Sunday following joint training with Turkish military ships in the Mediterranean.

The US has ramped up its military presence in the Middle East as the Israel-Gaza war continues. An aircraft carrier, the Abraham Lincoln, and its strike group are presently operating in the region’s waters of US Central Command, according to Navy Times.