Talks for Turkey to transfer its Russian-made S-400 missile system to the United Arab Emirates (UAE) in exchange for American F-35 fighter jets have stalled, according to people familiar with the matter cited by Semafor, Turkiye Today reports.

The discussions, which began last month, were seen as a path toward clearing the way for Turkey's purchase of the American F-35 fighter jets. However, the negotiations have reportedly failed to advance.

US President Donald Trump's plans to sell the jets to Turkey remain stalled more than a month after he announced them, leaving Congress to navigate the resulting tension between a NATO ally and Israel.

S-400 requirement at heart of standoff

At issue is a requirement in US sanctions law that Turkey offload its Russian S-400 system to gain access to F-35s, six of which it has already paid for and that have remained in the United States since Turkey's expulsion from the program in 2019.

Disabling the S-400 is one possible solution to facilitate the Trump-backed sale, though one that risks further stoking tension with lawmakers who view the statute as requiring full divestment of the system.

Another option is selling the Russian system to the UAE.

The Wall Street Journal (WSJ) reported July 18 that Turkey was in talks to transfer the system to the UAE, but Semafor reported those conversations don't appear to have advanced, according to people familiar with the matter.

The US removed Turkey from the program to buy and help build the F-35 in 2019 after it bought the S-400 from Russia.

The US worries that operating both advanced technologies side by side in Turkey could allow the S-400 to learn key details of the F-35, including its radar signature, and share them with Moscow.

The discussions with the UAE came after Trump visited Turkey in July for the NATO leaders' summit, at which he said he planned to lift restrictions on the country's purchase of US jets.

US Congress members weigh in

US lawmakers continue to be skeptical about the prospects of the deal.

"I don't think they should have F-35s unless they're going to be a true partner … so if they have the S-400, they cannot have the F-35," Sen. Rick Scott, R-Fla., said.

Senate Foreign Relations Chair Jim Risch, R-Idaho, who has held a longstanding hold on the purchase, told Semafor: "At this point, they have not removed the S-400s, so it's at a standstill."

Why UAE talks may have stalled

The situation is also complicated by foreign policy factors. Trump previewed the F-35 sale at last month's NATO summit alongside Turkish President Recep Tayyip Erdogan, according to Semafor. A few hours after that, Israeli Prime Minister Benjamin Netanyahu raised the stakes by warning that selling Turkey the jets could "destroy the power balance in the Middle East."

The Republican Party-controlled US Congress has largely given Trump what he wants during his second term, but the F-35 sale could have a hard time surviving a congressional disapproval vote that would pit Israel's interests against a NATO member, in part because many Trump allies are among those insisting on Turkey's full divestment of the Russian system.