On July 30, Lindsey Graham was in his office in Washington when he pressed his ear to a phone. A staffer named Debbie patched the senator through to a man waiting on the other end of the line, and Hulusi Akar, the defense minister of Turkey, introduced himself.

Akar urgently wanted to speak to Graham about a matter that had divided his country and the United States. Earlier that month, Turkey, a NATO ally of the U.S., had finally gotten a delivery of a Russian-made S-400 missile system, designed to take out American-made F-35 fighter jets. Turkey's ordering of the Russian missiles had been a huge boon for its relationship with Moscow, but America, a far richer and more powerful ally, was furious and threatening sanctions.

Graham had been monitoring the situation closely. In the days before Akar called, Graham had talked to the Turkish foreign minister and was trumpeting the offer he’d made him: Don’t activate the Russian missiles and sign a free-trade agreement with the U.S. instead. Several big questions loomed: Was that offer still on the table? Was Trump willing to put his political weight behind such a deal? How far was the president willing to go to support his counterpart in Turkey, the strongman Recep Tayyip Erdogan? It seems Akar thought—perhaps not unreasonably—that Graham might be able to give him some insight into Trump’s thinking and that of his colleagues on the Hill. After exchanging some pleasantries with Akar—whose stilted English was delivered with a tough-to-place accent—Graham made clear that he was in a position to help.

Of course, there was one important fact the caller didn’t mention. He wasn’t the defense minister of Turkey. He was Alexey “Lexus” Stolyarov, one half of a Russian phone-prankster duo, along with Vladimir "Vovan" Kuznetsov. They had made their name pranking extremely high-profile people, including Sir Elton John and French president Emmanuel Macron. Their ability to access these people, and the substantive foreign-policy discussions they would lure them into, has made observers wonder if Lexus and Vovan had connections to—and orders from—the Russian security services.

Reached on Thursday, a spokesman for Graham confirmed that the senator had been fooled. “We have been successful in stopping many efforts to prank Senator Graham and the office, but this one slipped through the cracks,” Kevin Bishop said in a statement. “They got him.”

On the call, the two men wasted little time in getting down to business.

“So as far as I understand, President Trump has entrusted you with this negotiations,” the man Graham assumed was Akar said, according to audio of the 16-minute call.

“Yeah, sort of,” Graham drawled. “Let me tell you what he told me: ‘I don’t wanna impose sanctions on our ally Turkey.’ ” Graham repeated the offer he had floated publicly: Don’t activate the S-400 and get a free-trade deal instead.

The man with the accent was skeptical.

“Yes, but what has President Trump said about free-trade agreement?” he asked.

“Okay,” Graham said. “So, he told me to call President Erdogan and make this offer.”

The purported defense minister was pleased to hear this, but was concerned about how Erdogan might react if there were even the whiff of sanctions. He wanted Graham to understand: Russia was not Turkey’s enemy, and Turkey was in a dangerous neighborhood.

“I don’t know what to tell you other than I am doing all I know to do and President Trump is very sympathetic to the situation of President Erdogan, but the Congress is not sympathetic,” Graham said. “Democrats are not sympathetic at all, and we’ve lost some Republicans here when it comes to Turkey. And Turkey’s too valuable of an ally to get in a dispute with.”