This is why the rest of the world cares about America's choice of president: what President Barack Obama decides on Syria is what matters.
It probably comes down to a couple of A4 sheets on the Oval Office desk, one under the heading "downsides".
On it will be two columns and the first - downsides to not striking Syria - will be short: "look weak, irrelevant, uncaring". But the second - downsides to striking - will be very, very long.
Let's start with the people who voted for Obama. They celebrate his disentangling the US from Iraq and Afghanistan. They do not want to get mired in yet another far-away mess. Nor do they want to pay for it. The US army is rationing biros right now, never mind Tomahawk missiles.
Then there is Russia. Next week, Obama will be in St Petersburg for a G20 summit. If torpedoes have already rained down on Russia's good friend Syria, there will be no pleasantries between him and President Vladimir Putin. He would be on Russian soil when relations between Washington and Moscow are at their lowest ebb since the Berlin Wall came down.