The Kurdish militia captured the border town of Ras al Ayn on Sunday, which had been under rebel control since last November. A day later, the United States said it was "very concerned" at reports that the militia was about to declare self-rule in northern Syria. "Such a declaration is highly provocative, as it will certainly exacerbate tensions between Arabs and Kurds," Jen Psaki, a State Department spokeswoman, said Monday. Turkey, which embarked on a broad peace process in March with Kurdish militants at home, has warned that it won't tolerate an autonomous Kurdish province across the Syrian border. This...