Turkey mounted on Wednesday its largest military effort yet in the Syrian conflict, sending tanks, warplanes and special operations forces over the border in a United States-backed drive to capture an Islamic State stronghold in Syria . The offensive on the city of Jarabulus began hours before Vice President Joseph R. Biden Jr. was set to meet with President Recep Tayyip Erdogan in Ankara to discuss tensions raised by the failed coup in Turkey last month. The joint operation in Syria seemed intended to send a message that the countries are still cooperating in the fight against the militant group. Turkish officials said the operation started at 4 a.m. with Turkish and United States warplanes pounding Islamic State positions in Jarabulus. The special operations troops entered Syria to clear a passage for a ground operation by Turkish-backed rebel groups, the state broadcaster TRT reported. The assault comes […]