In ideal circumstances, any attack on Syria would be preceded by a careful buildup.
The president would patiently lay out convincing evidence that the Assad regime murdered civilians with chemical weapons. He would build public support and get authorization from Congress. And he would make a forceful case under international law, rally allies and get approval from the United Nations, or at least from NATO.
But that is not how the response to Syria's chemical weapons attack will play out. Nor should it.
The list of reasons is long.
The U.N. part, of course, is impossible. Russia and China will block any Security Council resolution, and NATO isn't a viable option, either. U.S. credibility was so damaged by the false allegations used to justify the Iraq War that any approval would take months, if it is possible at all.
While the international bodies dithered, the U.S. would look like a helpless oaf, stumbling over its own red lines, which would encourage further atrocities - and not just in Syria. Instead, the U.S. is gathering what allies it can, though even British participation looked doubtful Thursday after the House of Commons refused to endorse military action.
The domestic situation is more complex but no less fraught.
Obama and top administration officials laid out the evidence for congressional leaders Thursday, and hopefully they will set aside their usual partisan gamesmanship. At a moment like this, national unity matters. But the need for some kind of formal congressional approval is dubious, as is the value.
It would be almost unique for a president to seek approval in these circumstances - not for a war, at least as Obama sees it, but for a short, sharp missile attack designed to punish the regime and deter further use of chemical weapons. A long line of presidents have committed military forces to limited interventions without consulting Congress.
President Reagan invaded Grenada and controversially stationed Marines in Beirut, where they were killed. President Clinton fired cruise missiles at Sudan and Afghanistan in response to al-Qaeda attacks on U.S. embassies in Africa, and at Baghdad in response to Saddam Hussein's attempt to assassinate the first President Bush. Clinton also launched an all-out aerial assault on Kosovo, in concert with NATO. The list goes on.
Nor would a congressional resolution guarantee a better outcome. Presidents cited congressional resolutions as de facto declarations of war to justify the calamitous U.S. invasions of Iraq and Vietnam. The attempt to secure one would also come with the risk that the least responsible members of Congress would politicize it.
Congress couldn't even begin to debate until it returns from recess on Monday, likely co-mingling the argument with sharply partisan conflicts over the budget and debt limit.
Sometimes, a president just has to act on his best judgment as commander in chief. In this case, Obama does not need to respond instantly. He does not have to get ahead of the evidence being compiled by U.N. inspectors in Syria. He does not have to squeeze the attack in ahead of a foreign trip that begins this week.
But if and when the facts are persuasive, he needn't delay. The surest way to have an impact on bullies like Assad is to respond to their provocations as fast and hard as the circumstances allow.