The overarching theme of last week’s NATO summit was revitalization. After years of uncertainty, with the U.S. under Donald Trump all but turning its back on the alliance, and even some European members expressing doubts about its future, there is the sense again that NATO is the keystone to maintaining the western-led international order. But it is weakened, and the proverbial vultures are circling.

Russia in particular sees an opportunity to fracture NATO, with a strategy of deepening the crisis between Turkey and key members like the U.S. Is Russia using Turkey to destroy NATO?

Adnan R. Khan: Firstly, what are the weak points that Russia believes it can target to weaken NATO?

Ilter Turan: For some time now, there have been strains in NATO solidarity. We might remember Emmanuel Macron calling NATO as having experienced brain death. Donald Trump sent a message that the American commitment to defend Europe may not be as reliable as assumed. Turkey’s purchase of the S-400s added another layer of division.

With all of these issues, Russia senses an opportunity to weaken NATO and it appears to have chosen Turkey as the instrument to do it. In fact, a rather high-ranking member of the Russian government recently intimated that the problem standing in the way of Turkish-Russian relations is NATO. But when we examine Turkish behavior, we observe that it lives up to all of its commitments within NATO. It takes part in all NATO exercises, and considers NATO as a resource which it can call on in the event its security is challenged by regional actors, which does not exclude the Russians.

So, despite the shortcomings of NATO its weakening solidarity, which the Americans are now trying to restore – it is still the case that Turkey views the alliance as an important resource to achieve security. At the same time, it seems that NATO is growing increasingly cognizant of the important contribution Turkey’s membership makes to NATO’s defense, particularly in view of the fact that the EU has limited defense capabilities. Jens Stoltenberg, NATO’s secretary general, recently acknowledged that it is Britain, Turkey and the U.S. that are the main defenders of Europe.

Adnan R. Khan: The UK-Turkey relationship is relatively stable, but the relationship between Turkey and the U.S. is at historic lows. How do we explain that relationship through the NATO lens?

Ilter Turan: I think when we talk about NATO, obviously we’re talking about a community of nations, but within that community, there are bilateral relations, too. There are a number issues between Turkey and the U.S. that have really little to do with NATO. The only exclusive NATO issue seems to be the S -400. There are, of course, other issues that transcend bilateral relations and also affect NATO, like the conflict in the eastern Mediterranean, which pits two NATO allies against each other. So in the complicated world of international relations, it’s not surprising that there are disagreements between the U.S. and Turkey on a number of issues.

The S-400 is, of course, is not just an American-Turkish issue. Other NATO allies have also suggested that it is not a good idea to acquire an air defense system which, firstly, cannot be integrated into the NATO system; secondly, would possibly compromise NATO security; and thirdly, would be produced by a country that is defined as an adversary of NATO. These are serious problems.

Adnan R. Khan: Indeed, it seems to be a weak point that Russia can exploit to divide NATO allies. Do you think fixing the S-400 issue is going to be sufficient to fix the relationship between Turkey and NATO, and the U.S. in particular?

Ilter Turan: No. But the S-400 is intimately connected with the F-35s, and more generally to the need for NATO countries to renew their air capabilities. If Turkey is kept out of the F-35 system, then it will have to turn to other sources. The only serious option available on the market comparable to the F-35 is the Russian Su-57. Already, after India dropped out, Russia is looking to Turkey to purchase Su-57s, an outcome that would only deepen the rift between Turkey and NATO.

Adnan R. Khan: So putting all this together, if, as Stoltenberg says, Turkey is a critical component of European defense, then the Russian push to sell Turkey the S -400s is a way to peel Turkey away from NATO and thus severely weaken the alliance. Turkey is the Achille’s Heel. How can that change such that Russia stops trying to meddle in Turkey’s affairs?

Ilter Turan: I’m not persuaded that Russia will ever stop, but I think their hopes of pushing Turkey further away from NATO may be vitiated if the as S-400 crisis is resolved and if Turkey is re-integrated into the F-35 program. The U.S., as the superpower within NATO, can utilize its influence to influence the behavior of other members toward Turkey. I think the new American president is aware of this and was the reason why the EU postponed considering applying more sanctions to Turkey in its upcoming meeting. There seems to be an effort to bring Turkey back into the NATO fold and keep it out of the Russian sphere.