This actually encapsulates the difference between a classic liberal and a left-wing radical pretty succinctly.
The classic liberal believes that there should not be a war in society, nor a state of unrest approaching a war. There are rules of good behavior, within a society. There are lesser rules of good behavior owed to foreign actors (as in a war against an alien state). But within the actual “family,” a higher standard of conduct is required towards one’s fellow citizens.
The leftwing radical of course holds the opposite — nearly every leftwinger believes that war against foreign states is somehow illegal, and that we owe greater standards of good conduct to those outside the family.
And within the state? They believe in the rules of war.
They fundamentally see their fellow citizens — at least those not part of The Cause — as hostile enemies to be defeated By Any Means Necessary. And that includes violence, where needed.
Or to put it another way, as we noted in mid-2009, Obama, following Alinsky’s lead, is the inverse of von Clausewitz — he’s always eager to view American politics as the continuation of warfare by other means.