One feature of many of these wars is that we're not attacking the state itself. We're attacking groups within the state. For example, in a drone strike in Somalia three days ago (didn't read about that one, did you?), we killed someone in al Qaeda. At other times we kill Somalians who are in al-Shabab.

These are groups that, on the one hand, don't have the capacity, as a state government might, to retaliate in an immediate and specific way. But that doesn't mean retaliation won't be forthcoming. Indeed, groups such as al-Shabab, whose political goals are essentially local, may now become more inclined to consider America the enemy and begin planning anti-American terrorist attacks, or trying to recruit home-grown terrorists in America.

The blowback could assume vaguer form, as well. When we kill Muslims abroad, it often winds up being fuel for al Qaeda recruiting--especially when, as will inevitably happen from time to time, bystanders or family members get killed in the process.

In either event--whether there is distinct retaliation or diffuse blowback--it takes awhile for these chickens to come home to roost. That's very different from classical acts of war, where the attack is on the state itself and tends to lead to immediate retaliation.

This time lapse changes a president's decision-making paradigm. When the downside of attack is delayed, attacking becomes more attractive. The president can launch strikes to impede terrorism in the short run and let the blowback show up on the next president's watch. (I'm not saying the calculation is always this consciously cynical, but the result can be the same even when it's not.)

So the good news, I guess, is that many of these things are acts of war in only a technical, legalistic sense, because they aren't actually attacks on other states. The bad news is that this makes them more attractive to a president and thus increases their number. And the worse news is that this, in turn, may in the long run actually increase the number of anti-American terrorists out there. Which in turns makes the drone strikes even more attractive to a president. And so on.