President Donald Trump suggested on Thursday that he was likely to permit Turkey to purchase F-35 fighter jets as soon as “the end of the day,” ending a nearly eight year blockade on Ankara’s acquiring the top-of-the-line fighter jet as a result of its 2017 purchase of a Russian S-400 missile system.

Speaking to reporters from the Oval Office alongside Turkish President Recep Tayyip Erdogan ahead of a meeting between the two and their respective teams, Trump said without mentioning the F-35’s or the less-advanced F-16 jets by name that he expected the Turkish leader would “be successful with buying the things” he would “like to buy.”

“He needs certain things, and we need certain things, and we’re going to come to a conclusion. You’ll know by the end of the day,” Trump said at the outset of his meeting with Erdogan. 

The White House declined to comment on what the president was referring to or if an announcement regarding resumed F-35 sales to Ankara was imminent. 

Erdogan has focused his visit to the White House, his first such trip in six years, around securing U.S. sanctions relief and approval for new arms deals, including the F-35 jets and other fighter and Boeing aircraft. Trump implemented the sanctions during his first term after Turkey purchased a Russian air defense system that U.S. officials warned could be used by the Russians to harness data on the F-35’s capabilities and compromise the aircraft.

The sanctions, pursued through the Countering American Adversaries Through Sanctions Act, are still in place due to Turkey’s refusal to replace the Russian system. The Biden administration approved the sale of F-16 jets to Turkey in early 2023 on the condition of Ankara allowing Sweden to join NATO.

The prospect of Trump changing course on the sale has sparked bipartisan concern from some lawmakers. While some see such a sale as a way to incentivize better behavior from Ankara, others have warned that the embrace could have the opposite effect.

A bipartisan coalition of House lawmakers wrote a letter to Secretary of State Marco Rubio and Defense Secretary Pete Hegseth on Thursday urging the Trump administration against approving a deal for F-16s or F-35s. 

It was signed by Reps. Chris Pappas (D-NH), Gus Bilirakis (R-FL), Dina Titus (D-NV), Nicole Malliotakis (R-NY), Brad Sherman (D-CA), Frank Pallone Jr. (D-NJ), Don Bacon (R-NE), Jim Costa (D-CA), Josh Gottheimer (D-NJ), Stephen Lynch (D-MA), Dan Goldman (D-NY), Brian Fitzpatrick (R-PA), Brad Schneider (D-IL), Tom Suozzi (D-NY), Wesley Bell (D-MO), Ted Lieu (D-CA), Mike Lawler (R-NY), Rob Menendez (D-NJ), Greg Landsman (D-OH) and Gabe Amo (D-RI). The American Jewish Committee, CUFI Action Fund and FDD Action were among the organizations that endorsed the letter.

“The security risks of Turkey’s acquisition and continued possession of the Russian S-400 system are well known. The S-400 poses a direct threat to U.S. military aircraft, including both the F-16 and F-35, by enabling Russian intelligence to gain insight into sensitive U.S. military technology if operated alongside these platforms,” the lawmakers wrote. 

“Congress has consistently upheld bipartisan restrictions on Turkey’s access to the F-35. Any move to reverse this policy without first securing the statutorily required certification would be a clear violation of U.S. law, undermine Congressional authority, and signal to others that U.S. law and strategic principles can be disregarded,” they added.