The United States on Tuesday moved to head off preparations for a suspected Russian military buildup in Syria as Bulgaria agreed to an appeal from the Obama administration to shut its airspace to Russian transport planes. The planes’ destination was the Syrian port city of Latakia. The administration has also asked Greece to close its airspace to the Russian flights, Greek and American officials said, but Greece has not publicly responded to the request. The apparent Russian military preparations and the Obama administration’s attempt to block them have escalated long-running tensions between the White House and the Kremlin. Although the United States and Russia agree that the Islamic State is […]