Washington: United States Defence Secretary Lloyd Austin has discussed support for Turkey's military modernisation in a phone call with Turkish Defence Minister Yasar Guler, the Pentagon said late on Monday.
It comes after Turkish President Recep Tayyip Erdogan agreed to send Sweden's accession protocol for joining NATO to parliament for approval.
The US stance on Turkey's military modernisation
US President Joe Biden's administration has backed Turkey's desire to purchase 40 new Lockheed Martin Corp F-16 fighter jets along with modernization kits for its existing warplanes from the US.
"I stand ready to work with President Erdogan and Turkey on enhancing defense and deterrence in the Euro-Atlantic area," Biden said on Monday.
However, some in Congress, mainly Senate Foreign Relations Committee Chairman Bob Menendez, have opposed the move over Turkey blocking NATO membership for Sweden, its human rights record and its relations with Greece, among other concerns.
Mendez, a Democrat, said that he was "continuing to have reservations" on providing the fighter aircraft to Turkey.
"If they (Biden administration) can find a way to ensure that Turkey's aggression against its neighbors ceases, which there has been a lull the last several months, that's great but there has to be a permanent reality."
Menendez added that there needs to be a way to "beef up Greece's security" and obtain "assurances about future actions."
What Turkey said about F-16 jets from the US
Meanwhile, Turkish President Erdogan said on Monday that his country's ratification of Sweden's NATO membership bid and the sale of F-16 jets are not to be linked to each other.
He made the comments before leaving for the NATO summit in Vilnius.
Erdogan is expected to hold further talks with Biden at the meeting on the purchase of F-16 fighters.