If Congress were now to give advance approval to the red line with Iran, the mullahs will understand that there will be no stopping the president from keeping his word. Only if the mullahs believe that President Obama will attack their nuclear reactors if they cross the red line will there be any hope of deterring them from doing so.

The goal is not to have the president actually attack Iran. It is to persuade them that he will do so if they challenge him by crossing the red line.

President Obama has already shown Iran that he is willing to take military action against Syria without the approval of the Security Council, Great Britain, NATO, the Arab League and other representatives of the international community — as long as he has the approval of Congress.

This is especially important with regard to Iran, because Congress is more likely to support military action against Iran’s nuclear weapons program than is the international community.