ANKARA, Turkey — Delivery of a second Russian-made S-400 air defense system to the Turkish military may face a delay over technology transfer disagreements, Turkey’s top procurement official said.

Ismail Demir, president of the Undersecretariat for Defence Industries, said the delivery, originally scheduled for 2020, may experience a delay due to Turkey’s ongoing negotiations with Russia over technology transfer and co-production options as part of the S-400 deal.

“We are planning a timeline for next year. As opposed to the first [batch], there is joint production and technology transfer here. It is beyond the ‘let’s buy it quickly and install it’ of the first system,” Demir told private broadcaster NTV. “The joint production concept may move the timeline. We have some sensitivities regarding some of the production being here. Technical work continues.”

Turkey announced in December 2017 it would acquire the Russian system. It received the first S-400 in July but has not yet installed it.

In response to Turkey’s acquisition of the S-400, the United States suspended Ankara’s partnership in the American-led, multinational Joint Strike Fighter program that builds the F-35 fighter jet.

Turkish President Recep Tayyip Erdoğan reiterated Nov. 11 that his government’s decision to buy the S-400 system was irrevocable. His comments came ahead of a planned Nov. 13 visit to Washington where he will meet President Donald Trump. Presidential sources in Ankara said the S-400 dispute, and Turkey’s request for readmission into the F-35 program, will be one of the “hot topics” in Erdogan’s meeting with Trump.

Prior to its suspension from the F-35 program, Turkey committed to buy more than 100 F-35As. Turkey’s local industry produces parts for the program, including airframe structure and assemblies, landing gear components, and more than 100 F135 production engine parts to include titanium integrated blade rotors. Businesses there also produce missile remote interface units, the panoramic cockpit display, center section wiring systems, airframe structures and assemblies, hardware for the F135 engine, and an advanced precision-guided standoff missile meant to be internally carried by the F-35 aircraft.

Political observers in Ankara said the S-400 shipment delay may be intentional.

“Turkey may deliberately not wishing to have the deliveries as planned,” a Turkey specialist said. “Ankara is reluctant to fuel tensions with Washington.”