In its editorial Tuesday, May 29, The New York Times says that the decision by the United States, Britain, France and at least five other major nations to expel senior Syrian diplomats was still short of the tougher diplomatic and economic sanctions needed to put real pressure on President Bashar Assad and his cronies. Beyond this step, a powerful sign of international revulsion at the massacre of more than 100 Syrians in the village of Houla, a United Nations arms embargo and the toughest possible comprehensive economic sanctions are long overdue. Russia has the most leverage, but, inexcusably, it still sells arms and coal to Syria and uses its Mediterranean port of Tartus. Russia can finally help, or continue to be a roadblock to tougher action.