Turkish President Recep Tayyip Erdoğan is railing against the U.S. issuing arrest warrants Thursday against 12 members of his security detail for their role in a furious melee during his May visit to Washington, vowing to “fight politically and judicially” against the move.

Nine demonstrators were injured in the violence when Erdoğan’s bodyguards attacked a crowd protesting his visit to the capital on May 16, sparking outrage in the U.S. and straining diplomatic relations between the NATO allies.

In televised comments Thursday night, the Turkish president questioned the decision to issue the warrants, and said the detail had been there to protect him.

“Why would I take my guards to the United States if not to protect myself?” Erdoğan said.

“They didn’t do anything [to the protesters]. In addition to that, yesterday they detained two of our brothers who intervened… they issued arrest warrants for 12 of my security officials. What kind of law is this? What kind of legal system is this?”

Here’s what you need to know about the escalating row.