Andrew Bacevich considers why American military action has gone awry so often in the last twenty years:

How can we explain this yawning gap between intention and outcomes? Fundamentally, a pronounced infatuation with armed might has led senior civilian officials, regardless of party, and senior military leaders, regardless of service, to misunderstand and misapply the military instrument. Force is good for some things, preeminently for defending what is already yours. Not content to defend, however, the United States in recent decades has sought to use force to extend its influence, control and values.

There are a few things that account for this tendency to favor and endorse military options. One reason is the great disparity in power between the U.S. and the states that it typically confronts. Weak states, or at least states that are significantly weaker than the U.S. and its allies, have been the preferred targets for military intervention over the last two decades. It is much easier to support launching “limited” strikes, air wars, or even full-scale invasions against smaller, often ill-equipped, and outmatched forces than it would be if an adversary were much better-armed and capable of inflicting significant damage in response. On a related note, the U.S. and its allies enjoy enough economic and military advantages that they can “get away” with squandering resources at a rate that would be prohibitive for most others, and as long as they are able to keep “getting away” with such wastefulness there will always be a temptation to indulge in it. Another reason is the assumption that the U.S. will not be exposing our country to serious retaliation when it launches attacks on another state. Finally, there is a bias in our political culture and in foreign policy debate more specifically in favor of taking “action” rather than being “idle,” and unfortunately “action” has typically been understood in terms of military action and little else. Unless the U.S. takes military action, or is at least actively aiding one side in an ongoing conflict, it is frequently accused of “inaction” regardless of anything else that the government may be doing on that issue. As long as non-military options are equated with passivity, they will keep losing out over time to calls for “action.”

Take the intervention in Libya, for example. That was a good example of how the U.S. and its allies resort to the use of force “because we can” rather than because of any necessity or worry about our own security. While there may have been some concern that the Libyan government might respond to military intervention by employing terrorism in reprisal attacks, there was never much of a chance that it could effectively retaliate against the states that attacked it. As long as policymakers pay no attention to the other consequences of this kind of intervention, which “worked” in the narrow sense of toppling the government, they are likely to continue overestimating and overly relying on military force as an effective tool for promoting “influence, control, and values.” Where skeptics and opponents see failures or foolish destabilizing wars that should never have been fought, proponents of these sorts of interventions point to them as proof that they can “work.”