The United States has repeatedly warned Turkey that the Russian S-400 system it aims to buy would compromise the security of the F-35 aircraft, which is made by US company Lockheed Martin.
US officials speaking to Reuters news agency on the condition of anonymity said the next shipment of training equipment and all subsequent shipments of F-35 materials have been cancelled.
“Pending an unequivocal Turkish decision to forgo the 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,” the spokesperson said on Monday, Al Jazeera reported.
Ankara, which is a production partner in the making of the stealth jet as well as a NATO ally, has so far refused to back down on its planned purchase.
The move comes just days after Turkey’s Minister of Foreign Affairs Mevlut Cavusoglu said Ankara was committed to a deal to buy the Russian system and was discussing delivery dates.
Last week, four US senators introduced a bipartisan bill that would prohibit the transfer of F-35s to Turkey until the US government certifies that Ankara will not take delivery of the system.
The disagreement over the F-35 is the latest diplomatic dispute to strain US-Turkey relations.
The two countries are at odds over the Middle East policy, including the war in Syria and sanctions on Iran, and Ankara has demanded the US extradite Fethullah Gulen, a former imam it accuses of orchestrating an attempted coup.
The US decision on the F-35s is expected to complicate Cavusoglu’s planned trip to Washington this week for a NATO summit.
Reuters reported last week that Washington was exploring whether it could remove Turkey from the production of the F-35.
Turkey makes parts of the plane’s fuselage, landing gear and cockpit displays.
In an attempt to persuade Turkey to drop its plans to buy the S-400, the US offered the pricier, US-made Patriot anti-missile system in a discounted deal that expired at the end of March.
Turkey has shown interest in the Patriot system but not at the expense of abandoning the S-400.