President Obama said part of America's obligation as a leader in the world was to make sure that a Government was held to account when it used prohibited weapons.
The US is considering a "limited act" in response to the alleged use of chemical weapons by the Syrian army, but how will Assad respond?
Will America go it alone in Syria after the Government's defeat in the Commons last night? The answer is yes. Emphatically yes.
As the West wakes up to another day, it is not just Prime Minister David Cameron who has a Syria problem - so does President Barack Obama.