This is very different from 2003.
1) We have video of the rockets being launched.
2) We intercepted the orders to carry out the attack.
3) The military operation contemplated here is a specific targeting, not an invasion.
4) There is no history of the decision makers having a personal bias or prior beef with the leadership in Syria.
5) We are not relying on suspect information from unreliable third parties to determine what happened.
Different indeed
Hussein repeatedly violated UN Security Council resolutions.
-- not the case with Syria
The US and UK made a forceful case to the UN for military action and the issue was thoroughly debated
-- not the case with Syria
W made a long and thorough case for war with Iraq.
-- Obama has barely done so; he's made on short speech to the public about it.
Iraq fired upon US forces daily prior to our use of force
-- Assad's forces have made no attacks on US forces
The US assembled a coalition of 29 countries for military action in Iraq
-- To date Obama has 3 including the US and no indication that 2 of those will also be involved militarily.
The majority of Americans supported military action in Iraq even without a UN authorizing resolution.
-- A much stronger majority of Americans oppose our military involvement with Syria.
Senate voted 77-23; House 297-133 for Iraq Authorization
-- I'm betting the Syria authorization will be much tighter.
Just a few differences that show why Iraq is indeed a bad analogy - it had much more justification and support than what Obama is advocating.
Of course they are also not comparable due to the scale of the mission. Iraq was a huge mistake; Syria will be a mistake.