The Turkey-U.S. Dispute over Use of Russian S-400 System - Wasilewski, Karol (Polski Instytut Spraw Międzynarodowych, 2019)
At the end of May, Turkish soldiers began training on the S-400 defence system, purchased by Turkey from Russia. This was followed by a negative reaction from the U.S., which implemented countermeasures. The U.S. is urging Turkey to withdraw from the transaction, signalling that it will lead to a negative re-evaluation of bilateral relations. The problems in relations with Turkey may induce the U.S. to deepen its alliance with Greece and could lead to tensions within the transatlantic community, as well as weaken Turkey's involvement in NATO.