Sen. Lindsey Graham (R-SC), who has criticized President Donald Trump’s decision to pull U.S. troops out of northern Syrian because of its impact on the Kurds, reportedly privately undercut his own support for the ethnic group during what he believed was a phone call with the Turkish defense minister.

As Politico reported on Thursday, Graham was the victim of a prank phone call by two notorious Russian rogues in August. The pranksters, who go by Lexus and Vovan, have tricked a number of high-profile western leaders into taking their calls by pretending to be foreign dignitaries. In Graham’s case, the duo succeeded in getting the senator on the phone by impersonating Turkish Defense Minister Hulusi Akar.

Graham, who sits on the Senate Foreign Relations Committee, spent a sizable portion of the call attempting to dissuade Turkey from using the new S-400 anti-aircraft weapons system it purchased from Russia at the objections of the U.S. and NATO. Towards the end of the call, however, the senator also broached the subject of Turkey’s longstanding “problem” with Kurds in northern Syria, even stating the ethnic group was a “threat”

“Your YPG Kurdish problem is a big problem,” Graham told the pranksters. He was referring to the Kurdish People’s Protection Units, a group that began fighting ISIS as part of the Syrian Democratic Forces in 2015—with support from the U.S.—but is considered a terrorist group by Turkey because of its push to establish an autonomous state for the Kurds on the Turkish-Syrian border. “I told President Trump that Obama made a huge mistake in relying on the YPG Kurds,” Graham continued. “Everything I worried about has come true, and now we have to make sure Turkey is protected from this threat in Syria. I’m sympathetic to the YPG problem, and so is the president, quite frankly.”

The comments, as Politico noted, undermine the tough posture Graham has taken in recent days against Trump’s decision to withdraw U.S. troops from northern Syria and redeploy them elsewhere in the country. Graham has argued against such a maneuverer, which involves the redeployment of less than 25 U.S. troops and amounts to an abandonment of the Kurdish forces that have fought against ISIS since at least 2013.

In particular, Graham and other backers believe such a redeployment will incentivize Turkey, who has also fought ISIS and Bashar al-Assad’s forces in Syria, to move against the Kurds. To prevent such an action, Graham has threatened to lead Congress in imposing sanctions against Turkey if they were to attack the Kurds.

“While the Administration refuses to act against Turkey, I expect strong bipartisan support,” Graham said on Wednesday when outlining his plan for sanctions. “Most Members of Congress believe it would be wrong to abandon the Kurds who have been strong allies against ISIS.”