I'll take it as the modern-day equivalent of the firing on Fort Sumter.
I think it would be a ghastly mistake for the Democrats for so many reasons that it would be difficult to catalog them all. Briefly, though: it would rally and motivate Conservatives like nothing else; it would not merely distract attention from Obama moving his agenda through Congress, but would absolutely poison the already-strained relations in that body and make future retaliation likely; it would make Democrats appear weak to our foreign adversaries who would thus be emboldened to act against our interests; and it would further polarize the nation at a time of great financial distress which will likely worsen this summer.