(Not sure if this is the right place for the question, but the roots of it are political.)

From what I've seen, Turkey's decision to buy the Russian S-400 anti-air system has jeopardized its relationship with its NATO allies, and earlier today the US went further and decided to stop training Turkish pilots on how to fly the F-35. I don't understand why. I can see why Turkey choosing to buy a rival's weapons are an embarrassment to NATO, but I don't see why we have quotes like this (from the source):

Kathryn Wheelbarger, one of the Pentagon’s most senior policy officials, said last week that Turkey’s completion of the transaction with Russia would be "devastating," dealing heavy blows to the F-35 programme and to Turkish interoperability within the NATO alliance.

"The S-400 is a Russian system designed to shoot down an aircraft like the F-35," said Wheelbarger, an acting assistant secretary of defense. "And it is inconceivable to imagine Russia not taking advantage of that (intelligence) collection opportunity."

  • Why would Turkey possessing the S-400 deal a heavy blow to the F-35 programme? If anything, it would be a security risk for Russia, since now a NATO country will have a detailed idea of how the S-400 works, how dangerous it is, what its limitations are, and so on.
  • Even if we assume that Turkey starts testing how effective the S-400 is at shooting down the F-35, it still doesn't explain how Russia is going to get hold of that intelligence.
  • Even if Russia can get hold of that intelligence, it doesn't explain why refusing to train Turkish pilots on how to fly the F-35 does anything (unless this is completely a political tool to pressure Turkey). In other words, does Turkey possessing the S-400 but not the pilots to fly the F-35 accomplish anything?

If we leave aside the political embarrassment, why would Turkey possessing the S-400 be a problem for NATO?

  • 1
    FYI there have been a number of S-400 related questions in recent months. There are no dups insofar as I can tell from a cursory scan, but you might find some of the answers to them interesting. Commented Jun 7, 2019 at 4:39
  • 2
    In the current climate where the US is very trade (war) oriented, part of any US motivation could also simply be that someone is buying foreign when they could/should be buying from the US... but this is just my rough superficial impression, so I leave it as a comment in case someone wants to pick it up to flesh out a full answer. Commented Jun 7, 2019 at 9:28
  • The U.S wants them to buy arms from them and not Russia. Commented Nov 17, 2019 at 0:38

3 Answers 3


If Turkey has both the S-400 air defence system and the F-35, it will be able to test the two together. The US is worried that the opportunity to gather extensive data on detecting the F-35 with the S-400 system will allow Russia to improve its ability to detect and track that aircraft, and potentially other US aircraft too.

  • 2
    I'm accepting this since although it doesn't answer the second bullet point, the linked article does. Thanks for answer!
    – Allure
    Commented Jun 10, 2019 at 7:33
  • 3
    It's still imperative to include critical parts into the answer itself -- because that information would be lost and the answer rendered useless <s>if</s> when the link rots. Commented Sep 22, 2019 at 17:16
  • They can track all USAF jetts also taking off from Ankerlick airbase
    – Suhayb
    Commented May 20, 2020 at 22:02

A modern weapon system consists of hardware, software, organization, and training. A new SAM would have to be integrated into the NATO-wide air defense system. If Turkey were to work with the Russians to integrate S-400 into the Turkish part of the NATO system, they would have to explain to the Russians how the NATO air defense works.

In theory, they could discuss SAMs without revealing any fighter secrets.

In practice, if they spill secrets in one area, they are no longer considered trustworthy in other areas.

  • 3
    Doesn't it work the other way around, though? Isn't Russia also exposing their military secrets to Turkey?
    – Obie 2.0
    Commented Jun 7, 2019 at 7:13
  • 1
    @Obie probably, however, as Russia seems to be OK with exporting the S-400 system to the NATO member Turkey, it seems that they have either have a sanitized export-version, or they consider the S-400 system not that critical.
    – Dohn Joe
    Commented Jun 7, 2019 at 8:22
  • 1
    @Obie2.0 I'm sure that Turkey won't get the source code for the software part of the S-400. Turkey will require constant maintenance from Russia for the S-400 which will allow Russia to get diagnostic data etc. Commented Jun 8, 2019 at 10:31

I am not sure whether I can technically answer your question or not, but here is mine.

If you take a glimpse at history, You will understand that, the EU is a big continent with lots of small countries (~30) and had seen some extreme wars. Post WW2, they all united into one unit (EU) to ensure they all stay together for the next war, if any.

Soviets had plans to conquer the EU nations and other countries. They were successful to some extent. EU nations (With support from the US and other allies) were successful in fending off the soviets from their land. US was strongly against Soviets and they don't believe them no matter what. (Cuban missile crisis, etc)

Post WW2, The Americans and EU's formed many treaties and bodies to ensure they work together and to stand against their enemies Together. As a part of this deal, Americans, EU nations provided the much needed financial aid and gave free access to their allies, so they can prosper and be potential allies to them when needed. As a part of this deal, the US provided their niche weaponry to combat for its (considered) allies like Turkey and others on (highest priority).

Some countries gobbled the (generous?) resources provided by their allies (US and EU) and when in distress, they started to slide with their opponents(For more resources? like a parasite?). (Greece threating to leave EU, Turkey threating to release migrants into EU). Providing (Financial/other) aid was never an issue with the Americans/EU nations. Forgiving 100 Billion debt to Greece wasn't an issue for EU. But, they want to enforce responsibility so they live within their means. They did everything to ensure the bad blood doesn't spread. But some countries started to take leverage of the generosity of others and started blackmailing with threats.

F35 is a niche war weapon from US. F35 is like a sniper, which is very good at doing one job (considering its cost). Other warfighters from the US like F22's or F16 are more like Green berets. They can survive in any environment and can combat in any situation. In a war, you can let your green berets anywhere. They are capable to fight in any situation. But revealing your sniper's position could change the game completely.

Now, why would the US allow countries like turkey to have access to its F35's (Snipers)? Once your not so ally is aware of your weaponry weaknesses/limitations, it could just jeopardize the whole strategy.

If US loses a dozen F16's or F22's, no one bothers about them. But If US loses 3 F35's, everyone will lose their mind. It could change the perspective of the US (citizens) and its allies completely. Strength is a perception. If it fades, you aren't commanding anymore. To ensure no such thing happens, you wanna conceal your weaponry. You shouldn't reveal any weaknesses. So, the US doesn't sell its F35's to any country which procures weaponry from Russia (and China?). Access to F35's was given only to (considered) essential needed allies. (Turkey, Singapore, some EU nations, UK, etc). Now, some of them started to misuse the privilege. How do you feel?

If you look from a shop's perspective, A shop selling only "Brand A" products will attract only "Brand A" fans. A shop selling "B Brand" products will attract only fans of "B Brand". If a third shop starts selling products of Both brands A & B, who is going to lose? What happens in war? The one who procured niche weaponry from both the US and Russia will be stronger than US or Russia. Why would the US force itself into such a situation? Also, if Russia is the new vendor, they could demand a sneak-peek into F35's. Anyways turkey has jeopardized its relationship with the US and they need to mend fences with Russia, so yes. they will allow. Where will it lead?

Can F35's Fend off missiles from S400? I think, Yes. Will the US ever confirm that? NO. If they confirm, S-500 development will begin immediately. Why would they do that? Forget about the data of both S400, F35's etc. They were never in a war. (Except for some surgical strikes, which doesn't reveal anything)

In conclusion, This is a strategic move from all parties. Sadly, for the US, they had to take this route despite supporting them for decades. They want to ensure no such misuse happens from now on, so they are limiting access by imposing additional restrictions(Stopped training, spares, etc).

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .