Paul Krugman is warning that the Euro might collapse in a matter of days.
The problem is that Europe put itself at the mercy of the financiers. All governments borrow; it is a fact of life. When they can't borrow, they run into trouble. When they run into trouble, they can't borrow.
Somebody put out a rumor that Spain might default. So the interest rates on Spain's borrowing starting going up. The higher the rates go, the riskier Spain's debt looks, so... the higher the rates go. So now, Spain might actually go bankrupt, due to a run on their national treasury, just like even the good banks in the Great Depression went under.
This can't happen to America. We can always print money to pay off our old bonds. Sure, it would piss people off and cause inflation, but the solution only has to be temporary. Once it's clear we aren't going to default, the pressure drops, and we can stop printing money. Since the financiers don't want us to print money, that stability point will come pretty quickly. So, we're protected: despite the best efforts of the lunatics who want to abandon fiat money (and thus leave us completely at the mercy of anyone who can corner the gold market), America is still safe.
But Europe isn't. Whole governments will fall, people will suffer, but the financiers will win. They'll make money speculating on the collapse, and then they'll buy national assets for pennies. And then they'll do it all again.
And we worried about Islamic terrorists...