China on Tuesday advised its citizens in Afghanistan to leave the country “as soon as possible,” following a coordinated attack by Islamic State militants the previous day on a Chinese-owned hotel in the heart of Kabul. The Chinese advisory appeared to be a setback for Afghanistan’s Taliban rulers who seek foreign investments in hopes of halting the downward spiral of the Afghan economy since their takeover of the country more than a year ago. The militant Islamic State group — a key rival of the Taliban — claimed responsibility for the attack Monday afternoon on Kabul Longan Hotel, which left...