U.S. President Joe Biden told his Turkish counterpart in a call on Monday that the latter would have to drop its objection to Sweden joining the NATO to be able to buy F-16 fighters.
The exchange reportedly took place when Biden called Erdogan to congratulate him on his victory in Turkey's presidential election on Sunday.
Ankara sought new F-16s after the U.S. rejected its proposal to buy F-35s for its purchase of Russian S-400 missile systems.
"I congratulated Erdogan. He still wants to work on something on the F-16s. I told him we wanted a deal with Sweden, so let's get that done. And so we'll be back in touch with one another," Biden told reporters before departing the White House.
After Russia invaded Ukraine, Sweden and Finland applied for NATO membership, ditching long-held policies of military non-alignment. Bids for membership must be approved by all 31 NATO members. Turkey and Hungary have yet to approve Sweden's bid.
Turkey is against Sweden joining the alliance because it believes the Nordic country harbors the Kurdistan Workers Party (PKK), which took up arms against the Turkish state in 1984, a charge Sweden denies. The PKK is designated a terrorist group in Turkey, Sweden, the U.S. and Europe.
Sweden has also criticized Turkey for human rights abuses and over democratic standards, irking politicians in Ankara.