For the geo political minded. Excerpts from a large, but interesting article.
"For the 500 or so days since Turkey and Russia signed an agreement for the acquisition and eventual deployment of the Russian S-400 air and missile system, the United States has sought to convince Turkey to back out. The United States is concerned that the Russian-made S-400 will collect valuable electronic intelligence about F-35, the American-made fighter jet Turkey is slated to receive in November. Talks between Washington and Ankara have taken place at the presidential level, amongst different elements of the civilian bureaucracy, between the two militaries, and at the parliamentary level — with no success. At this point, the United States needs to start planning for the day after the first S-400 is delivered. This exercise should inform U.S. thinking about how to plan around an increasingly recalcitrant Turkey and prepare for a future in which Ankara remains a NATO member, but one that operates an advanced Russian system that could help Russia glean useful data about the alliance’s air operations. Turkey risks legacy and current U.S.-Turkish defense co-production and development programs if it continues to deepen defense cooperation with Russia. For the United States, the situation is less bleak — in fact, searching for alternatives to Turkish military assets provide some strategic opportunities in Eastern Europe and the Middle East. Still, working around Turkey will be financially and politically costly for NATO. The deepest, most intractable problem is what the dustup reveals about Turkey’s lack of commitment to the core NATO tenets of interoperability, burden-sharing and collective defense — an outcome that weakens the entirety of the alliance, including the United States......
Deepening Turkish-Russian Defense Ties
Since the late 1970s, in procurement negotiations with Western aerospace firms, the Turkish government has prioritized co-producing and developing defense equipment in Turkey. In the case of S-400, Ankara departed from this historical norm and agreed to weaker co-production terms than it had previously demanded of firms in the United States and Europe. This is disconcerting, but could actually help shield legacy U.S.-Turkish defense cooperation from being negatively impacted by the deal with Russia. However, if Ankara were to actually reach agreement for the co-production of combat aircraft, like the Russian Su-57, as the foreign and defense ministers have hinted is being discussed, things could get worse. Foreign Minister Mevlut Cavusoglu has underscored a willingness to explore deeper ties with Russia. In an interview with Turkey’s NTV that “if the F-35s don’t work out, I will again have to procure the jets I need from elsewhere … There are [Russian] SU-34, SU-57 and others. I will absolutely meet my needs from somewhere until I can produce it myself.”
Sergei Chemezov, the CEO of Russia’s Rostec Corporation, has suggested that his firm would consider a request from Turkey “about the production localization or technology transfer” for the Su-57 jet. Chemezov also added that Moscow would consider working with Turkey on S-500, a surface to air missile still under development in Russia, and which President Recep Tayyip Erdogan has cited as missile Turkey intends to “co-produce with Russia.” Moscow has an incentive to hold key technology back, owing to Turkey’s membership in NATO and legitimate concerns that the United States could exploit Russian-origin technology in Turkey.....
....if the two sides were to reach an arrangement similar to the now-defunct Russian-Indian partnership for the production of an Su-57 variant that involves Turkish aerospace firms, the risk to U.S.-Turkish defense programs will grow more acute. Specifically, If Ankara were to reach agreement with Russia to co-produce components of either of these systems, the United States could decide that Russia could gain access to U.S. origin defense equipment, resulting in the revocation of licenses for U.S.-controlled technology.
All of this matters for the United States. Independent of the bilateral tensions, Washington has a very strong interest in each NATO member having a strong military, capable of working closely with the United States. But a weakened Turkey, faced with American sanctions, could choose to deepen its reliance on Russia. This outcome will benefit Russia, but at this point, Moscow is playing with house money because of Ankara’s initial decision to purchase the S-400.
America’s Options: NATO’s New Eastern Flank
Beyond the risk to legacy defense cooperation, the United States will soon have to contend with how to plan NATO training exercises if it can’t trust Turkey to protect the F-35. The first and most tangible outcome may require moving the F-35 engine maintenance facility from Eskisehir, Turkey, to the Netherlands. As part of Turkey’s participation in the F-35 consortium, it is currently slated to serve as Europe’s primary engine maintenance hub. This is certain to change, given the concerns about flying allied F-35s in and out of S-400-patrolled Turkish airspace. Second, in any future NATO air exercise in Turkey, NATO countries could simply choose not to send F-35 for joint training.
It would be imprudent not to expect Ankara to take some retaliatory measures, most likely aimed at aspects of the U.S.-Turkish defense relationship. Retaliating in this fashion is complicated because of Turkey’s NATO membership and the terms in the Defense and Economic Cooperation Agreement (DECA). The agreement limits U.S. military activities in and from Turkish military bases to NATO-related missions, meaning the Turkish government must approve any so-called “out of area” missions. In theory, Turkey could retaliate against the withholding of F-35 by preventing the United States from using Turkish territory for combat operations in the Middle East. This reaction would ensure that Turkey’s role within NATO remains intact, but also that the United States feels some pain for the forthcoming sanctions.
This would mean Turkey would still host an American operated TPY/2 radar because it supports NATO’s effort to field ballistic missile defense to protect European populations from missile attack. The radar provides early warning and discrimination data for the two Aegis ashore missile defense sites at Romania’s Deveselu Air Force Base and Poland’s Redzikowo Air Force Base. These two bases also provide the United States with options to work around Turkey. Romania and Poland are two countries that would welcome an increased U.S. presence. The United States should consider increasing funding to support American and NATO air operations from the Polish and Romanian air bases."NATO's eastern flank has been discussed here previously- It has the convenient aspect of working to keep Russia in check
Going back to 2014: US Paratroopers go to Poland & Poland Largest Nation on NATO Frontline
"Both Poland and Turkey are frontier NATO states, with Poland being described as “the largest and most important NATO frontline state in terms of military, political and economic power.” These two geostrategic states also have an overwhelming population when compared to their neighbors, as well as national inferiority complexes stemming from their lost imperial legacies (the Polish-Lithuanian Commonwealth and the Ottoman Empire). They share a significant land border with the states targeted for a ‘democratic transition’, as well as important cultural and political connections with those societies (as a result of the aforementioned imperial legacies)"2018: NATO Needs a Strategy for Countering Russia in the Arctic and the Black Sea
Eastern Flank con't:
"This move would increase U.S. basing options in Europe, while using the Russian entente with Turkey as an opportunity to increase NATO presence along the alliance’s eastern periphery. In essence, Washington could flip the script and use Russia’s outreach to Turkey to its advantage, deepening its presence in eastern Europe and reminding Moscow of American capabilities at the edges of Russian territory....."
Greece- An alternative to TurkeyReaders have certainly been informed of this possibility!
Recently: One and Two reports on the topic
"Greece could emerge as another attractive candidate. One option is Andravida Air Force Base, which hosts the INIOHOS multinational exercise involving aircraft from Cyprus, Italy, Israel, and the United Arab Emirate, alongside the Hellenic and American Air Forces. A second option is increasing the U.S. footprint at Larissa Air Base. The Air Base currently hosts U.S. drones, as their permanent base in Africa undergoes repairs. Moreover, according to the local Greek Daily, Kathimerini, there are talks to base KC-135 tankers at Larissa. A U.S. presence at either Air Base would offer increased protection from long-range Russian missiles, while also increasing the U.S. footprint in the Mediterranean NATO member."