A vicious crackdown on protesters by Turkish guards — in the U.S.

This is not how diplomacy works.

On Tuesday, members of Turkey President Recep Tayyip Erdogan’s armed security detail viciously beat up protesters, putting some in the hospital.

But it didn’t happen in Turkey, where Erdogan’s increasingly authoritarian government shows little patience with dissent. It happened in Washington, outside the residence of the Turkish ambassador. Erdogan was in town for a visit with President Donald Trump.

Speaking too freely might be grounds for a beating in Turkey. But in the U.S., it is a protected right. Erdogan’s guards — and a group of supporters who joined the melee — should be charged with crimes.

In video of the attack, it’s easy to spot Erdogan’s guards. They’re the ones dressed in dark suits who are risking scuff marks to their polished shoes as they kick and hit defenseless men and women curled up on the ground. They’re the ones who overwhelmed the Washington cops who tried to intervene.

The guards likely have been flown out of the country, and they or others may have diplomatic immunity. But the Washington police and U.S. officials should treat them like common criminal suspects nonetheless. Even if diplomatic immunity protects them from prosecution, they can be kicked out of the country for good.

“Violence is never an appropriate response to free speech,” the State Department said in a statement, promising to scold the Turkish government “in the strongest possible terms.”

The White House has been silent, likely not wanting to strain a cordial relationship between Erdogan and Trump. But Sen. John McCain of Arizona didn’t hold back. “This is the United States of America,” he wrote on Twitter. “We do not do this here.”

And four other senators have demanded an apology, but fat chance of that.

In a statement on Wednesday, the Turkish embassy blamed the protesters for the attacks and said the guards — the only people there with guns tucked under their suit coats — were acting in self-defense. The video says otherwise.

Erdogan is engaged in a tough crackdown in Turkey. More than 110,000 people have been detained since a failed coup attempt last year.

But he’s not allowed to crack heads in the United States.