Senate Foreign Relations Committee Chairman Bob Menendez is adamant about blocking the F-16 fighter jet sales to Turkey even though the latter stated it would swiftly consider Sweden joining NATO, according to Defense News on Wednesday.

Menendez continues to block selling the most advanced 4th generation US-made fighter aircraft, according to the report, which cited Menendez saying: “I’ve always said that the ratification of Sweden, which should naturally occur, is not the sine qua non of why I would lift the hold on F-16s". 

“There are bigger issues than just that alone," however, he did agree to a $259 million sale of avionics software upgrades for Turkey’s current F-16 fleet, per Defense News.

The delivery of F-16 fighter jets was a topic of conversation during a phone call between Turkish President Recep Tayyip Erdogan and US President Joe Biden on Sunday, according to the Turkish presidency. The two leaders also addressed Sweden and Ukraine's applications for NATO membership.

The Turkish leader also criticized attempts to link Sweden's membership to Turkey's request for F-16 procurement and praised Biden for supporting Ankara's demand for F-16 fighter jet shipments. That said, Biden strongly supported the F-16 sales to Turkey back in January. 

Turkey even expressed anticipating a 'positive outcome' back in April, when Turkish Foreign Minister Mevlut Cavusoglu said: "In fact, there is no such thing as complete blocking. We know that the [Biden] administration is making sincere efforts. They are determined to provide Turkey with F-16s or kits required to modernize the existing Turkish aircraft. There are those who are against it in Congress, but we know, that the administration is making an effort regarding those who are against it. We also expect a positive outcome". 

Back in February, Democratic and Republican senators sent a letter to Biden saying that both Sweden and Finland were taking "full and good faith efforts" to meet the requirements to join the military alliance that Ankara asked for, despite Turkey asking Stockholm for more concessions.

"Once the NATO accession protocols are ratified by Türkiye, Congress can consider the sale of F-16 fighter jets. A failure to do so, however, would call into question this pending sale," the letter read.