The U.S. State Department dismissed increasingly aggressive rhetoric from Turkish President Recep Tayyip Erdogan directed at America as something Washington is “used to,” following a threat from Erdogan that U.S. forces would soon experience the “Ottoman slap.”

In remarks to the Turkish Parliament on Tuesday, Erdogan appeared to be rebuffing U.S. Lt. Gen. Paul E. Funk, who had told media that American troops had no intention of leaving Manbij, northern Syria, where Erdogan has threatened to invade. Erdogan has already sent forces into Afrin, east of Manbij, to fight the U.S.-allied Syrian Kurdish People’s Protection Units (YPG/YPJ).

Erdogan has repeatedly demanded the U.S. withdraw from northern Syria, even though the government of Syria has denounced Turkey’s presence there as illegal and demanded Erdogan withdraw (Bashar al-Assad has said the same of the United States).

“It is clear that those who say ‘we will respond aggressively if you hit us’ have never experienced an Ottoman slap,” Erdogan told the parliament. “We will destroy every terrorist we have seen, starting with the ones standing by their [the Americans’] side. Then they will understand that it is better for them to not to stand alongside the terrorists.”

The “Ottoman slap,” the Kurdish outlet Kurdistan 24 explains, “was a potentially fatal martial arts technique used in close combat by Asappes, unmarried paid soldiers, in case they became unarmed while leading assaults on enemy positions in conquests into Europe from the 16th century onward.”

State Department spokeswoman Heather Nauert refused to answer whether the United States has, indeed, experienced an “Ottoman slap” in its history during her regular press briefing on Tuesday, though the martial technique and the American state did not co-exist at any time in history. Instead, she noted that Secretary of State Rex Tillerson will visit Ankara this week, a sign of how severe the deterioration in relations has come since Turkey invaded Afrin.

Asked again whether the escalating belligerence in Erdogan’s tone alarmed the State Department, Nauert said, “Okay, I think we’re used to that kind of rhetoric, whether it’s from the Turkish Government or from other governments, and so that’s why we don’t get too riled up about that.”

“We hear other governments, other foreign leaders say things about us, post things about us on social media, all of that. It’s not going to get us riled up. We’re sticking to the policy,” she concluded.

Pressed on whether Erdogan’s language was precedented for a NATO ally, Nauert said, “It doesn’t matter, doesn’t matter. We’re not going to go there; we’re taking the high road.” She also reiterated that Turkey has unspecified “legitimate security concerns” in invading Syria.

“We will talk with our ally about their legitimate security concerns and also our concerns about the escalation of violence,” she insisted.

The Trump administration has repeatedly used the term “legitimate security concerns” to refer to Turkey’s ongoing fight to eradicate the Kurdistan Workers’ Party (PKK), a U.S.-designated Marxist terrorist organization. Erdogan’s government considers the YPG and the PKK one organization, unlike the United States, and as such is using the PKK’s activity within Turkish borders as an excuse to invade Syria.

Erdogan initially claimed the Afrin invasion, dubbed “Operation Olive Branch,” was necessary because the United States and the YPG had organized a “border security force” to prevent foreign Islamic State jihadists from flooding the country and undoing the progress against the terrorists that the YPG made last year.

Tillerson himself criticized Turkey’s invasion of Afrin on Tuesday, asserting that “ISIS remains a serious threat to the stability of the region, our homelands and other parts of the globe” and that Turkey’s Olive Branch operation “detracted” from the goal of eradicating ISIS.

“We remain concerned over recent events in northwest Syria and call on all parties to remain focused on defeating ISIS,” he added.

Tillerson also demanded that the Iranian government and its proxies, including Hezbollah, vacate the crowded Syrian civil war theater.

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