A Turkish Air Force F16 jet lands at a new airport under construction in Istanbul
A Turkish Air Force F16 jet lands at a new airport under construction in Istanbul, Turkey September 22, 2018. Reuters

U.S. President Joe Biden said that in a call on Monday Turkish President Tayyip Erdogan repeated Ankara's desire to buy F-16 fighter jets from the United States, while Biden responded that Washington was keen to see Ankara drop its objection to Sweden's joining NATO.

The exchange took place when Biden called Erdogan to congratulate him on his victory in Turkey's presidential election on Sunday.

"I spoke to Erdogan. I congratulated Erdogan. He still wants to work out something on the F-16s. I told him we wanted to 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 for Delaware.

"We're going to talk more about it next week," he added.

Bids for NATO membership must be approved by all NATO members. Both Turkey and Hungary have yet to approve Sweden's bid.

Turkey has sought to buy $20 billion worth of F-16s and nearly 80 modernization kits from the United States, but the sale has been stalled due to objections from the U.S. Congress over Ankara's problematic human rights record and Syria policy, even though the Biden administration has repeatedly said it supports the sale.

A much smaller $259 million package including avionics software upgrades for Turkey's current fleet of F-16 fighter aircraft was cleared by U.S. Congress earlier this year, days after Turkey ratified Finland's NATO accession.

The Biden administration has repeatedly rejected any assertion of any "quid pro quo" between the sale and the NATO enlargement, although Turkish Foreign Minister Mevlut Cavusoglu in January said the U.S. side made it clear that an approval of NATO bids would be viewed positively by the Congress.

A bipartisan group of senators in a February letter to Biden said Turkey's failure to ratify the accession protocols for Sweden and Finland, which was still waiting at the time, would "call into question this pending sale", referring to the F-16s.

A source familiar with the discussions said the United States had previously told Turkey that it would be hard to get Congress to approve the F-16 deal if Ankara doesn't green light Sweden.

Sweden and Finland applied for NATO membership last year, ditching long-held policies of military non-alignment following Russia's invasion of Ukraine.

Turkey ratified Finland's NATO accession in late March, but has continued to object to Sweden, saying Stockholm harbors members of militant groups it considers to be terrorists. Hungary has also not yet approved Sweden's bid.

Seeing Sweden join NATO by mid-July when the alliance is due to hold a leaders summit in Lithuania is among the top priorities for Washington

The Turkish Presidency in a brief statement on the call between Biden and Erdogan said the two leaders agreed to deepen cooperation on all aspects of their bilateral ties, whose importance they said has grown even more in the face of regional and global challenges.