Chinese President Xi Jinping will open late Saturday a two-day regional security summit attended by Russia, Iran and other allies confronting rising tensions with the US over trade and Washington’s withdrawal from the Iranian nuclear deal. Armored vans lined the streets of the coastal city of Qingdao as world leaders arrived Friday for the 18th annual summit of the Shanghai Cooperation Organization (SCO), a regional security bloc led by China and Russia. Its member states also include four ex-Soviet Central Asian republics, Pakistan and India. Iran is an observer member. Authorities emptied an entire oceanside swathe of the city —...