Iran’s joint military command warned Thursday that all oil tankers moving through the Strait of Hormuz must use its approved routes or face a “forceful response,” again ratcheting up tensions over a waterway crucial for international energy supplies. The strait, the narrow mouth of the Persian Gulf, has emerged as one of the top issues in negotiations to reach a permanent end to the Iran war. The statement from the Khatam al-Anbiya military command, reported by Iranian state television, comes after both U.S. and Iranian diplomats met with mediators on Wednesday in Qatar. It wasn’t immediately clear what sparked the threat from Iran. However, the U.S. military's Central Command had put out a statement about having a meeting with officials from Mideast nations in Bahrain that said “leaders underscored their shared commitment to the free flow of commerce through the Strait of Hormuz.” That appears to have been the phrase to anger Iran, which is preparing for the funeral that begins this weekend for the late Supreme Leader Ayatollah Ali Khamenei , who was killed in the war's fir