The fragile understanding that was supposed to keep the Strait of Hormuz open collapsed further this week. On Tuesday, the US Treasury revoked the general license that had allowed Iran to sell its oil on international markets, just over two weeks after Washington issued the waiver as the centerpiece concession of last month’s interim memorandum of understanding with Tehran. The reversal followed a wave of attacks on tankers in the strait, including strikes on a Qatari LNG carrier and a Saudi-flagged crude supertanker.