S-400s, a story:

Everything started when Turkey downed a Russian jet, Su-24 in Nov 2015 for violating its airspace. Russians were repeatedly bombarding Turkman-led rebel groups by using Turkish airspace. Ankara issued several warnings. Then downed a jet.

What was US reaction?

US officials, on the record, initially supported Turkey’s arguments. But had different talking points while briefing reporters on background.

US defense officials undermined Turkey’s claim and said Russian jet was in Syrian airspace when it was hit. So much for NATO solidarity

What else US thought of Turkey’s downing the Russian jet?

They thought it was an overreaction to “a minor violation of its airspace”

What about NATO?

Oh, they were generous. They sent an air defence package against Russian incursions following the jet incident, including AWACS.

But NATO diplomats WORRIED Ankara was too aggressive to defend its airspace against the repeated violations

Next, Germany/Luxembourg declared that Turkey cannot count on NATO support if there is a conflict with Russia in Syria.

“NATO cannot allow itself to be pulled into a military escalation with Russia as a result of tensions between the two”

Briefly: You cannot invoke article 4

Btw, US and Germany earlier in October 2015, a month before the downing of the jet, pulled their missile defense systems from Turkey.

Not only US and NATO didn’t want to support Turkey against Russia, they also didn’t want to keep their missile defense systems in the country

Meanwhile, U.S. decides to establish a partnership with PKK’s Syrian armed wing YPG against ISIS. YPG seizes key cities along Turkish-Syrian border, creating concerns that YPG will be able to capture the whole border area.

Turkey looks for an exit. Then comes Russia again

Turkey wants to clear ISIS from Jarablus, but it couldn’t do that. Because Russians were threatening Turkish jets.

In fear of an emerging PKK state in its borders, Turkey decides to sign a reconciliation deal with Russia, in order to operate freely and seize the territory

As far as I gather from Turkish sources, Russians had a condition for the reconciliation deal:

• Turkey would need to make a major Russian arms purchase as compensation for the downed jet and the killed pilot.

Turkey takes the deal.

For Turkish officials in Ankara, after the coup attempt in July 2016, S-400 seemed like a good solution for Russian demands.

At the time; there was no CAATSA, US didn’t want to sell a defense system to Turkey, and no one brought up S-400s possible implications on F-35.

So until this point:
• US/NATO didn’t ensure Turkey about threats posed by Russia in Syria
• US partners with Ankara’s arch enemy. Turkey is fearful of a PKK state in itsborder
• US doesn’t want to sell an air system to Turkey (They didn’t even want to sell smart munition)

So, July 2017.

US learns that Turkey is going to purchase S-400s. What is the US talking point then?

“How do you interoperate in the NATO system?” asked then-US Defense Secretary Mattis.

No mention of F-35

Btw, at this point Turkey had already signed the S-400 deal.

• The deal was inked by April 2017
• Trump signs CAATSA in law, August 2017

US waits until November 2017 to issue a soft threat about F-35.

I was in Washington between 2014-2019.

NOT A SINGLE US OFFICIAL I talked believed that Turkey would actually buy S-400:

•“It is a bluff” for concessions.

• “I wouldn’t believe that for a second until I see with my own eyes that S-400s are actually in Turkey”

Turkish officials?

They didn’t also believed that US was actually going to sanction Turkey over S-400z

• “It is a bluff” to make us buy Patriots
• “They cannot force us out of F-35 program”

So on and so forth.

Both sides didn’t believe each other for a second

No genuine effort shown by both sides to resolve the S-400 crisis. Both thought the other was bluffing.

• US was wrong to underestimate Turkey’s resolve. Failed to understand Turkey’s security concerns
• Turkey needed to see that S-400 is a genuine threat to F-35

END