Ekathimerini.com:

Turkey has issued notices restricting air space and waters off its Black Sea coast, to allow firing tests, apparently on Friday, involving its Russian-made S-400 missile defense units, a week after they were transported to the area.

While Turkey already tested the surface-to-air weapons last year, further exercises could stoke tensions with NATO ally the United States, which sharply opposed the purchase from Moscow on grounds that the S-400s compromise NATO defense systems…

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