Smoke rises from the Syrian town of Ras al-Ain, in a picture taken from the Turkish side of the border in Ceylanpinar on October 11, 2019, on the third day of Turkey’s military operation against Kurdish forces.Ozan Kose | AFP | Getty ImagesA U.S. official and a Syria war monitor say there has been an explosion near an outpost where U.S. troops are located in northern Syria amid intense shelling during the Turkish offensive in the area.The official said a projectile landed near the outpost but it wasn’t clear who fired it. The official said no American troops were hurt. The explosion marked the first time a coalition base has come in the line of fire since Turkey launched its offensive into Syria on Wednesday.Syrian Observatory Director Rami Abdurrahman said there was intense Turkish shelling of the Kurdish-held town of Kobani Friday. He said projectiles landed near the coalition base on a hill at the edge of town.The Kurdish news agency Hawar reported that it was an artillery shell. Both the Observatory and Hawar said U.S. warplanes flew over the base immediately after the incident.U.S. President Donald Trump pulled troops back from the border this week, saying he wanted American forces out of harm’s way.