One thing I think is overwhelmingly clear from the events today in Egypt: the American alliance with Hosni Mubarak is over. The alliance was justifiable on strategic grounds. Mubarak was a dictator, but he retained just enough of a mask of legitimacy to tip the American calculation in his favor. But now the public has shown its overwhelming opposition to his rule -- not Iran-level opposition but something closer to Romanian-level opposition -- and his recourse is pure brutality:

Today President Mubarak seems to have decided to crack down on the democracy movement, using not police or army troops but rather mobs of hoodlums and thugs. I’ve been spending hours on Tahrir today, and it is absurd to think of this as simply “clashes” between two rival groups. The pro-democracy protesters are unarmed and have been peaceful at every step. But the pro-Mubarak thugs are arriving in buses and are armed — and they’re using their weapons.
In my area of Tahrir, the thugs were armed with machetes, straight razors, clubs and stones. And they all had the same chants, the same slogans and the same hostility to journalists. They clearly had been organized and briefed. So the idea that this is some spontaneous outpouring of pro-Mubarak supporters, both in Cairo and in Alexandria, who happen to end up clashing with other side — that is preposterous. It’s difficult to know what is happening, and I’m only one observer, but to me these seem to be organized thugs sent in to crack heads, chase out journalists, intimidate the pro-democracy forces and perhaps create a pretext for an even harsher crackdown.

There's no going back now. Either Mubarak will be driven from power, or he will hold onto power in such a way that the U.S. can't touch him anymore.

Unlike Leon, I think Obama's measured response to the failed Green Revolution was sensible. Iran was a political culture deeply divided between supporters and opponents of the regime, and one in which the accusation of pro-Americanism was powerful. The Egyptian populace seems almost totally united in opposition to Mubarak, with the only significant support coming from those in Mubarak's pay. The opposition has all the nationalist and religious legitimacy it needs. At this point Obama needs to forcefully cut Mubarak loose. The only delay, I would hope, is his slowness to respond to events, a trait he has consistently displayed since the campaign. Sometimes that caution has served him well, but here it hasn't. If Obama does not act soon it will be a black mark.