There is only one last non-military stop on this train: President Obama's initiative to organize so-called "crippling" sanctions against Iran.
These sanctions would penalize the firms that sell, carry and finance the half-million tons of gasoline that Iran must import every month. (Incredibly, this huge oil exporter and aspiring nuclear power refines only about half the gas it needs.) Such firms are vulnerable to international pressure: Two of the three Swiss firms that provide the bulk of Iran's gasoline have substantial investments in Canada, for example. If Canada joins the sanctions regime, Canada can bring great pressure to bear on these suppliers -- and thus upon Iran.