ISTANBUL — Turkish Airlines (THY), Turkey's national air carrier, announced on Monday that it had cancelled all flights between Istanbul and the city of Simferopol on the Crimean Peninsula until June 17 amid escalating tension.

Russian President Vladimir Putin has since signed onto a law for the annexation of Ukraine's strategic peninsula amid criticism and sanctions from the European Union and the U.S. Like other international communities, Turkey does not recognize the Russian-backed referendum for the annexation of Crimea to Russia.