A Russian warplane again violated Turkish airspace on Sunday, a Turkish foreign ministry official said late on Monday, prompting Ankara to summon Moscow's ambassador, Censor.NET reports citing Reuters.
It had done the same following Saturday's violation, and said Russia would be held "responsible for any undesired incident that may occur" if it were repeated.
NATO held an emergency meeting in Brussels of ambassadors from its 28 member states to respond to what Secretary-General Jens Stoltenberg called "unacceptable violations of Turkish airspace" after a Russian jet crossed its frontier with Syria on Saturday.
"Allies also note the extreme danger of such irresponsible behavior. They call on the Russian Federation to cease and desist, and immediately explain these violations," NATO said in a statement after the meeting.
The White House called the Russian move a "provocation," and U.S. Secretary of State John Kerry said it illustrated concerns about an escalated Syrian conflict.
"Had Turkey responded... it could have resulted in a shootdown, and it is precisely the kind of thing we warned against," Kerry said during a visit to Chile.
The Russian Defence Ministry said on Monday that an SU-30 fighter aircraft had entered Turkish airspace along the border with Syria "for a few seconds" on Saturday.
Moscow's unexpected move last week to launch air strikes in Syria has brought the greatest threat of an accidental clash between Russian and Western forces since the Cold War.
Russian war planes as well as those of the United States and its allies are now flying combat missions over the same country for the first time since World War Two, with Moscow repeatedly targeting insurgents trained and armed by allies of Washington.
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