The purpose of war isn't to spread democracy
The purpose of war isn't to spread democracy, but rather to defend those who can't defend themselves. The U.S. generally only engages in warfare when a country is destabilizing and absolutely needs our help, through warfare. After the Haiti earthquake, the appropriate response was, to send in humanitarian forces to help the people. After the hurricane in the Philippines, marines were deployed to prevent the death of thousands more innocent people. The U.S. does not simply invade a country to spread it's political views and democratic ideals, but to help the innocent people. It's perfectly fine for a country to have differing views from us, such as France, Canada or the UK without necessitating an invasion to force them to abide by our political views at gunpoint or with lethal force backing it. The U.S. only invades when it is absolutely necessary for humanitarian reasons, rather than to change the government. For all of our disagreements with Saudi Arabia or even North Korea, an invasion wouldn't change the people's hearts and minds, and cause them to want to avoid their harmful behaviors that afflict the average citizen. Only through education and the promotion of our ideals in a civil manner can we spread our political views, not through violence. None change their principles under the threat of violence, and few will listen to our arguments when we use a heavy hand and a iron fist to deliver them. The purpose of an invasion is to help the local people by overthrowing a corrupt government, to allow the people to make their own decisions. But if the people are not ready, all an invasion will do is generate a power vacuum that will be filled by the next dictator, which history has shown is often worse than the previous one. We cannot simply invade to spread political ideas, but we must invade to spread peace, and provide order to chaos.
There is no merit to an invasion when the people won't change their minds. Only by planting the seeds of revolution and desire for democracy can we realistically overthrow the political confines that the people seek to place themselves within. When that country begins to yearn and fight for freedom, our objective needs to be to assist them in achieving it, by whatever means is needed, violent or not, rather than simply use violence. When many question our lack of involvement in many countries, the simple answer is that we aren't involved because war isn't always the best option, and won't always help. The North Koreans won't suddenly stop believing that their leader isn't the Emperor of the world, and will revolt against any form of American or other occupation. Only by convincing the people they are wrong and then overthrowing the government can we achieve our objectives. Democracy is often the result of U.S. invasions, but it is not the purpose. If the U.S. is to overtake a country, than it will, in the meantime, establish a democracy, as it is the best form of government under the U.S.'s care we will not allow the people to fall to another dictatorship. But the purpose of war is never to spread democracy, but to protect people. When we invaded France during WWII, to oust the Germans, it was done so under the pretext that we were protecting the people, rather than to overtake France ourselves or even convert them to a democracy. Truly, France was still a kingdom at the time, as was the UK, but it as not our business to violently overthrow their governments, only to protect the citizenry from the oppression of the foreign powers. While France's democratic spirit no doubt received a boost from U.S. intervention, it was not the goal and not an appropriate goal by itself to enforce our political views on others through violence. It is not the thoughts of these people, but the humanitarian concerns from whence they suffer, that is our objective.
Politics is not the ends of violence, but an ends to more violence. While it may seem paradoxical to use violence to protect others, the logic is fairly simple. Dead man can't kill others, and those who are incapacitated or neutralized, be it in prison or who surrendered, can't continue the campaigns of their leaders, often genocidal. In the case of the nazis defeating their military was a means to an end, not an ends itself. We were more than happy to rebuild Germany and take these previous soldiers and put them back in service of their own people, rather than simply kill all of them after we won. The purpose of violence was to disrupt the physical means of the other sides from inflicting causalities on whomever they pleased and enacting force upon them to achieve their desired goals. When met with force we had to respond with force, violence to meet their violence, so as to prevent it from occurring. While it's sad that anyone had to die, it's better that it's the Nazi or oppressor than the innocent people, which is often the only rational decision we are left with. While it brings me and few others joy to actually take or condone the taking of another human life, it is often a necessary requirement to defeat our enemies and help innocent people.
The basic purpose of an invasion is for the defense of other people, the U.S. or otherwise, and to protect them form harm. To prevent the destabilization of their own country, and provide order to the chaos and madness, or to prevent a country form doing the same to another. We invade for humanitarian reasons, to help and assist, and not to spread political views. To uphold values, human values, our sense of empathy, morality and compassion that the majority of us can agree upon and to assist the local people. Our job is not to spread out political, religious or other ideological views to those who do not share them at the point of a sword or by the barrel of a gun, but by our gentle reassurance that our methods simply work best. If we can convince them to follow our means after successfully helping them after an invasion, than so much the better, but this is not the purpose. The purpose of violence is only intended to protect those who are suffering, to defend them from more violence, and for no other reason than that.
