On Tuesday, US Acting Defense Secretary Patrick Shanahan said he was confident that Turkey would cancel its plan to purchase the Russian system.
"I've had a number of conversations with Defense Minister (Hulusi) Akar and I really think we'll resolve this situation with our strategic partners," Shanahan told reporters, Press TV reported.
"I am very confident in the Patriot proposal that we've delivered to Turkey, its availability, its pricing, and very importantly, the industrial participation that comes along with the Patriot system."
Asked whether that meant he expects Turkey will buy the Patriot system, Shanahan said: "I expect we'll solve the problem so that they have the right defense equipment in terms of Patriots and F-35s."
Meanwhile, Turkey has said the S-400 will be delivered by Russia despite the US pressure on the NATO member. According to multiple reports, the production has been estimated to be completed in May for subsequent delivery to Turkey in July.
This comes after the US said Monday it had stopped shipment of equipment for F-35 equipment to Turkey over the country’s defensive cooperation with Russia.
Reuters cited two unnamed sources in a report, suggesting that the Turkish officials had been notified about the matter by their American counterparts “in recent days.”
“The next shipment of training equipment, and all subsequent shipments of F-35 related material, have been canceled,” read the report citing sources speaking on condition of anonymity.
Also, the Pentagon said in a statement, "Pending an unequivocal Turkish decision to forgo delivery of the S-400, deliveries and activities associated with the stand-up of Turkey's F-35 operational capability have been suspended while our dialogue on this important matter continues with Turkey."
Shanahan was also asked Monday about whether the US will deliver the F-35s planned for Turkey, and he replied, "I expect them to be delivered."
The row over the F-35 and the S-400 is the latest in a series of diplomatic disputes between Ankara and Washington.