WASHINGTON - A 13-year-old Israeli girl fatally stabbed in her bedroom in Kiryat Arba on Thursday was a US citizen, the State Department said.The girl, Hallel Yaffa Ariel, was attacked after an assailant climbed a security fence and entered a home in the settlement of the settlement, near Hebron. "We have now confirmed that she is a US citizen," State Department spokesman John Kirby said at a news briefing.