US President Joe Biden's administration will move ahead with the transfer of F-16 fighter jets to Turkey in consultation with Congress, national security adviser Jake Sullivan said on Tuesday, according to Reuters.

The announcement comes a day after Turkey agreed to drop its longstanding opposition to Sweden’s bid to join NATO and refer its application to approval by the Turkish parliament.

Turkey, which had been the main stumbling bloc on Sweden's path towards the alliance, had requested in October 2021 to buy $20 billion of Lockheed Martin Corp F-16 fighters and nearly 80 modernization kits for its existing warplanes.

Turkish President Recep Tayyip Erdogan later said that the United States had proposed the sale of the F-16s to Turkey in return for its investment in the F-35 program, from which Ankara was removed after purchasing the S-400 missile defense systems from Russia.

Speaking ahead of a summit of NATO leaders in Lithuania, Sullivan said Biden "had been clear that he supports the transfer."

"He has placed no caveats on this ... He intends to move forward with that transfer," Sullivan told reporters, as quoted by Reuters.

Relations between the US and Turkey had soured after Turkey's purchase of the Russian S-400 missile defense system that the US believes can be used to spy on Western defenses.

In response to the purchase, the US sanctioned Turkey’s military procurement agency and expelled Turkey from the F-35 program, under which Western allies produce the next-generation fighter jet's parts and secure its early purchasing rights.

Turkey has repeatedly made clear it will use the Russian system despite US threats of sanctions.

In June of 2021, Erdogan and Biden held what the Turkish President described as a "fruitful and sincere" meeting on the sidelines of the NATO summit in Brussels.

Meanwhile, US Senate Foreign Relations Committee Chairman Bob Menendez, a Democrat who has blocked the F-16 sale, said on Monday he was in talks with the Biden administration about his hold and that he could make a decision "in the next week."

Menendez had said he had concerns about Turkey that extended beyond Sweden joining NATO, including human rights and Turkish overflights of Greek airspace.

Some diplomats and analysts believe Erdogan had been using Swedish membership of NATO to pressure Washington on the warplanes, and that Biden made a deal.