Turkey has been formally suspended from the multi-national Joint Strike Fighter program after the first elements of the Russian-made S-400 air defence system were delivered to Turkey by Russian Air Force An-124 transports on July 12.

The action by the US is the culmination of a process started last month which saw Turkish trainee F-35 pilots locked out of Luke AFB in Arizona where the first two Turkish F-35As are based for pilot training, and processes were started to remove Turkish industry from the program. All Turkish JSF program personnel including those who work in the JSF Program Office (JPO) in Washington have reportedly been told to leave the country by July 31

Turkey plans to acquire 100 F-35As, and has reportedly expressed an interest in acquiring the short take off and vertical landing (STOVL) F-35B variant to operate from its planned Juan Carlos 1 class amphibious ships.

Turkey was the seventh international partner to join the JSF program after the UK, Italy, the Netherlands, Canada, Denmark and Norway, signing on as a Tier 3 partner in July 2002. In January 2007, Turkey consolidated that partnership by signing an MoU with the JPO to participate in F-35 production.

The Almaz-Antey S-400 Triumf long-range surface-to-air missile system, known as the SA-21 Growler in NATO parlance is considered one of the most advanced air defence systems in the world. The US has labelled the system as being “incompatible with NATO capabilities”, and is concerned Russian advisors working on the training and sustaining the Turkish S-400 program will be able to glean valuable intelligence on the F-35 through the use of the system’s advanced sensors.

“Turkey’s decision to purchase Russian S-400 air defense systems renders its continued involvement with the F-35 impossible,” a July 17 White House statement said. “The F-35 cannot coexist with a Russian intelligence collection platform that will be used to learn about its advanced capabilities. Turkey has been a longstanding and trusted partner and NATO Ally for over 65 years, but accepting the S-400 undermines the commitments all NATO Allies made to each other to move away from Russian systems.”

While other NATO nations such as Greece operate older Russian systems like the S-300PMU1 (SA-20), the capabilities of these systems is well understood in the west, and those countries are not currently F-35 operators.

“Turkey cannot field a Russian intelligence collection platform in proximity to where the F-35 program makes repairs, and houses the F-35,” Undersecretary of Defense for Acquisition, Ellen Lord said in a Pentagon briefing. “Much of the F-35′s strength lies in its stealth capabilities, so the ability to detect those capabilities would jeopardise the long-term security of the F-35 program.”

Currently seven Turkish companies are involved in manufacturing nearly 900 engine, landing gear, airframe and electronic components for the F-35 program, and Turkey was named as the location for the European regional F135 engine depot overhaul capability.

Perhaps most notably, Turkish Aerospace Industries (TAI) manufactures centre fuselages, composite skins, weapon bay doors, and fibre-placement composite air inlet ducts on contract to Northrop Grumman. TAI also manufactures almost half of all F-35 air-to–ground pylons and adapters.

Undersecretary Lord said that, by March 2020, Turkey’s industrial participation in the F-35 program will be “unwound”, and she estimated this could cost the Turkish economy as much as US$9bn (A$12.7bn) over the life of the program. Initially, US companies will take over the production of the Turkish-made components, but she said she hopes to compete this production to the remaining international partner nations.