President Recep Tayyip Erdogan said the Turkish parliament will abide by his pledge to ratify Sweden’s accession to the North Atlantic Treaty Organization if the US sticks to its commitments to deliver F-16 fighter jets to Ankara.

The US has indicated that approval of the Nordic country’s entry into NATO is a prerequisite for agreeing to sell the war planes to Turkey, whose delay remains the last major obstacle to Sweden’s membership.

“I hope that, so long as they remain true to their promises, our parliament will also remain loyal to the promise that was made,” Erdogan told reporters on Wednesday, according to Sabah newspaper. The president was referring to negotiations for purchase of new F-16 jets as well as Turkey’s July pledge to further the Nordic nation’s membership.

Erdogan’s comments underscore Turkey’s evolving approach to US administration’s pressure on Ankara to process Sweden’s entry soon after Turkish lawmakers reconvene next month.

Ankara wants a quick resolution to its request for F-16s from Washington, where US legislators led by Democratic New Jersey Senator Bob Menendez have so far blocked progress in negotiations. Corruption charges against the senator last week created an advantage that Turkey wants to seize, Erdogan said. Menendez temporarily stepped aside as Foreign Relations Committee Chairman.

Sweden wants to join NATO to deter any aggression from Russia. It filed an application following Russia’s invasion of Ukraine in early 2022 together with neighboring Finland, which was welcomed into the alliance in April. All member states have to agree on newcomers, and Turkey is the main holdout alongside Hungary.

The delay threatens to stoke tensions between Turkey and its US-led NATO allies, who are increasingly impatient to see Sweden as a member.

--With assistance from Firat Kozok.