Russia has placed ships and submarines capable of launching nuclear missiles in case Turkey under the cover of NATO decides to strike out against the Russian position. President Putin has been clear; Russia will use nuclear weapons if necessary if conventional forces are threatened.
If Ankara opts for a suicide mission of knocking out yet another Su-24, or Su-34, Russia will simply clear the airspace all across the border via the S-400s. If Ankara under the cover of NATO responds by launching the Turkish Army on Russian positions, Russia will use nuclear missiles, drawing NATO into war not only in Syria but potentially also in Europe. And this would include using nuclear missiles to keep Russian strategic use of the Bosphorus open.
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