Imagine a game with two players. One player is playing to win, the other is playing to a draw, without actually going in for the kill. Even if the first player is weaker than the second player, if the game goes on long enough the odds are on his side... because he is playing to win.
Einstein famously said, "I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones."
While some believed that this style of limited warfare is the product of the Cold War's Mutually Assured Destruction, in which war had to be scaled down for fear of unleashing a nuclear armageddon... this inability to finish the fight has become most pronounced when Western powers fight conflicts with third world guerrillas or terrorists.
There are several factors that explain why we stopped playing to win, and accordingly have begun slowly losing.
1. Instant Communications - Like sausage, wars used to be 'made' mostly out of sight. Individuals might have personal experience of a battlefield, but few outside the military would have much visceral interaction with the war itself. With the American Civil War and the Crimean War that began to change. Photography and popularized first person accounts began the process of bringing war into the "living room", horrifying and repulsing millions.
By the time the technology had developed to the point where video broadcasts could be conducted from the field, or any civilian could capture some of the action on a cell phone, the barriers had been breached.
Naturally it would be the more civilized countries which placed a higher value on life and did not censor their media, that would receive the worst of this exchange. While the guerrillas and terrorists can always intimidate and silence, and in any case tend to operate in cultures with higher mortality rates that place less value on human life, Western nations cannot and do not function so.
The result is that civilized countries begin practicing excessive restraint on the battlefield, this not only gives the enemy more freedom of movement, it creates an entirely new strategic doctrine that involves using civilians as human shields, hospitals and civilian areas as bases, and even deliberately generate atrocities in order to foster propaganda victories.
In this environment, propaganda victories become real victories if they harm the morale of a Western power. The more the civilized side restrains its forces, the more power and territory, the enemy gains.
2. Liberalism - While the welfare of civilians on the enemy side was a legitimate concern, it was never supposed to be a greater concern than the lives of our own soldiers. Yet Liberalism has managed to accomplish exactly that as on the battlefield, with civilized nations putting the lives of soldiers at risk to protect enemy civilians.
This development has turned the human shield from a punchline, into a potent defensive measure, and a propaganda offensive tool.
As liberalism routinely assumes that their home society is usually at fault, and that the stronger party is also the guilty party, a liberal culture cripples the very military that seeks to defend it.
Such wars may be legitimate or not, on an individual basis, but they bury the primary justification for war, that of self-defense or the suppression of a vital and active threat. By doing so they also shift the priority from the military to the diplomatic, and from military accomplishment to nation building through winning the hearts and minds of the enemy civilian population-- an approach destined to undermine any purely military approach. Wars are no longer fought in pursuit of victory, but in order to build a better world... and we stop playing to win.
3. The Supremacy of Diplomacy - War becomes a means of enforcing a diplomatic objective. When diplomacy fails, we go to war. When the enemy meets our demands, we end the war. Then we rinse and repeat the whole cycle all over again.
Since modern diplomacy was envisioned as a peacemaking tool, these demands must be peacemaking demands as well. This makes war inherently contradictory and disreputable, and creates situations in which we endlessly pursue peacemaking diplomacy to avoid war, only to be tricked, and then restart the peacemaking cycle again. When we finally try to break the cycle of hollow diplomatic charades with war, universal condemnation follows.
War then becomes a halfhearted effort to hurt the enemy just enough to convince them to give in to our peacemaking demands. Unfortunately when the enemy has no interest in giving in, the military campaign quickly becomes a painful bloody drawn out mess with no real objective except buzzwords such as "Stabilization" and "Reining in the Extremist Elements Who Stand in the Way of Peace."
The latest example of such a misguided military campaign could be seen in Gaza, but it can just as well be seen in Iraq, and for that matter Vietnam. If you're not playing to win, but assuming that the enemy will give up and come to the negotiating table, then you're playing to lose... particularly against an enemy who knows how the game is played, and knows that all he needs to do is stay alive long enough for you to give up and go away.
4. Forgetting How to Fight - When the USSR was dismantled, the Yeltsin government attempted to give away land to farmers, only to discover that after generations of collectivization, too few knew how to farm anymore.
So national skills can disappear under the boot of socialism. There was a time in American history when the instinctive response to an attacker was force. Today the instinctive response is to run away and wait for the police to take care of it.
After a generation we have very nearly forgotten what war is, and what it's for. Afghanistan and Iraq proved that our soldiers still know how to fight, but our politicians and military command have often forgotten. As war becomes subservient to diplomacy, as the culture of liberalism and instant communications bring war into the living room and treat all military actions as atrocities-- we lose the ability to play to win and to fight to win, instead snatching diplomatic defeat from the jaws of a military victory.
But Playing to Win is the only real game in town. As Western powers and civilized nations stop playing to win, the terrorists who do play to win, begin winning. Our advantages in resources, organization and numbers can only hold out for so long unless we too begin playing to win.