In a crisp and cogent 15 minute address, President Obama laid out his case for military action against Syria. It was a strong speech—even if not always forcefully delivered—because the president addressed all the thorny issues regarding US military action against Syria raised in the last two weeks; and he did so in language that was simple, clear and honest.

The President called up images of dying Syrian children to remind Americans of the inhuman horrors of chemical war. He explained why the use of chemical weapons violates international norms and conventions. He cited convincing evidence that the Syrian government and its military forces were the perpetrators of the August chemical weapons attack that killed so many Syrian citizens. And he sought to show why, if unpunished, this use of chemical weapons is a danger to the security of the United States. Here, even if he sought to touch every possible consequence of inaction, he was not unpersuasive: Assad would feel free to use chemical weapons again; other tyrants would be encouraged to employ them; American troops fighting on foreign soil may find themselves faced with chemical weapons attacks; nerve gas, if used, might impact on American allies neighboring Syria—Turkey, Jordan and Israel; and other countries, seeing Syria go unpunished, may feel free to pursue weapons of mass destruction, including nuclear weapons..

President Obama also sought to put to rest the concerns of many Americans that even a limited attack on Syria would be the first step in a slippery slope entangling America in another war; that a limited strike would not be effective—the US does not do pin pricks, he said—or that Syria or its allies could retaliate in damaging ways against America or Israel.

An important and perhaps unanticipated point the president made was that by going to Congress for support for military action he wished to restore balance in war-making authority between the President and Congres--in favor of the legislative body.

Finally, president left the door open for diplomacy. He described Russia’s readiness to urge Syria to give up its chemical weapons as an “encouraging sign which he and his secretary of state will explore over the next few days with their Soviet counterparts and with America’s French and British allies. He will also ask Congress to postpone any votes on military action resolutions to give diplomacy a chance. But, Obama said, America’s military stands ready to act in case diplomacy fails—a message to Russia that the military option remains on the table.

Whether the President’s speech will change many minds remains to be seen. But he made his case clearly; and there is now breathing space for a broader national debate on this difficult and divisive issue.