Russian Foreign Minister Sergey Lavrov on Saturday quashed the possibility of Turkey handing over its Russia-bought S-400 air defense system to the US.

He said that the 2017 purchase includes an end user certificate that prohibits the system’s sale to a third party without Moscow’s consent.

Lavrov was responding to reports that Washington proposed Ankara to hand over control of the system to the US for the country’s re-inclusion in the F-35 program.

“The arms contracts contain the end-user certificate paragraph,” TASS quoted him as saying on the sidelines of the 79th session of the UN General Assembly.

“In order to do something else with the products that are delivered under such a certificate, which mentions the country that has received these weapons as the end user, the consent of the country that sold these weapons is needed,” Lavrov said.

US Plan

According to Greek newspaper Ekathimerini, senior US officials proposed to their Turkish counterparts in July to either hand over the S-400 to the US or transfer it to the US-controlled sector at Incirlik air base in southern Turkey in exchange for reviving the F-35 deal.

Turkey was expelled from the F-35 program after it bought the Russian system.

Ankara opposed the US plan but didn’t dismiss it outright, Ekathimerini added, citing sources.

“Their Turkish counterparts refused and countered they would just keep them in the box inside Turkey,” the outlet quoted senior fellow at the American Enterprise Institute and former Pentagon official Michael Rubin as saying.

“The deal is not dead, however, as reviving the F-35 deal will be on the agenda for the United States and Turkey when leaders and security officials meet next week at the UN General Assembly.”

Turkish Response

Days after the story was broken, Ekathimerini reported that Turkish defense ministry sources refused to confirm or deny the development, stating that Ankara’s position on the matter remains unchanged.

“Currently, there is no change in the stance of the two countries regarding the S-400 and F-35. We have always stated that it is not right for allies to impose restrictions or sanctions on each other and that this is inconsistent with the spirit of the [NATO] alliance,” the Greek outlet quoted a source as saying.

“Our expectation is that our allies will take decisions appropriate to the spirit of the alliance and the common security perspective and that all restrictions, covert and overt, will be removed.”