President Obama’s vow to punish Syria for using chemical weapons has critics of U.S. foreign policy upset that America is yet again acting like an imperialist power. Their frustration is appropriate — but their accusation is not.

America is less an imperialist and more a hapless uncle trying to teach his wayward nieces and nephews the right moral lesson. But just as with the uncle, no one will thank America if it averts further catastrophe — but everyone will blame it if it doesn’t.