Brief history probably known by all here:
For a large part of our history America was essentially isolationist. We were more concerned about our borders (securing and expanding) than we were about the rest of the world. If you go all the way back to the 7 Years War (one theater of which was fought in North America and named the French and Indian War) you had a people who largely didn’t want to fight it, and then were ticked off when they got the bill (taxes) for a war they never wanted. That resentment boiled into a war of “get out of my house.” Our next major conflict started with a foreign power conscripting newly minted American Citizens (granted, they were previously British citizens and were fleeing conscription in the British Navy), and was once again a war of “leave us alone.” Our next war was the Mexican American War, fought largely over whether Texas was allowed to join the United States. The next war was the Civil War – entirely an internal conflict, followed by the Spanish American War in which Spain declared war on us. During WWI we wisely stayed out until we saw ~16 million service men dead and said “we should get a piece of that action,” and joined a war in which we had no strategic interest (except for defending our honor against a telegram), then negotiated possibly the worst treaty ever (thank you Woodrow Wilson). After that war we shrank our armies again back in line with their historic norms until we were bombed on December 7th 1941. We destroyed both Nazi Germany and Imperial Japan, and then largely brought the troops home. However, the risk of WW3 was on the table with the Soviets militarizing eastern Europe. From fear of being dragged into a conflagration even greater than WW2 we maintained a large standing army for the first time in our nation’s history, and jumped into several foreign wars (Korea, Vietnam, Iraq twice, and Afghanistan). This is clearly not an exhaustive list of our military action as a nation, but certainly hits the highlights. We never as a nation jumped into foreign wars until April 6th 1917, but it wasn’t until Korea that we jumped in relatively unprovoked. We maintained an active global military presence to try to prevent ourselves from being pulled into a similar situation.
How about now? The USSR is no more. While Russia is a large nation (population 140 million), the most likely targets of Russian aggression would be Poland (37 million), Ukraine (42 million) and Germany (80 million). These three nations on their own could form an alliance, and add Belarus (9 million) if they are interested. There is no need for America to be prepared to fight the USSR when there is no USSR. If European nations want American support to prevent invasion that support should be seen merely as backup, not as a primary deterrence to Russian aggression.
The other major theater remains in Asia with China instead of Japan. Here again a regional alliance should be more than sufficient to develop a regional balance of power. The most fundamental unit of war is the warrior, and that scales with population. China tips the scales at 1.4 Billion people, far larger than the US should ever plan on fighting on our own. Luckily India has a population of 1.3 Billion, and so should be a regional counter force to China. This first pass hides a demographic point – within a few years (~10) the military age population of India will be double that of China. But what if Japan does not want to be dependent on India for support? A regional alliance here would look like Japan (125 million), South Korea (51 Million), Philippines (107 million), Indonesia (265 million), Vietnam (98 million), Thailand (69 million), and Malaysia (32 million) for a combined total of 750 million people. While that would not be enough to invade China it should be enough to defend against any sort of incursion. Combined this would leave Asia balanced between China, India, and the South Pacific Alliance (that alliance by the way would have a GDP substantially larger than China’s).
The last two regions are Africa, and the Middle East. Africa is pretty easy to answer – we have no national interest in any events happening in Africa. There is no reason for us to get involved in an internal civil war in Somalia for example. In the Middle East we have maintained a presence largely to secure oil for the world. The reality is that should no longer be our concern. Each month we have net imports of ~1 million barrels of oil and products (gasoline, diesel fuel, jet fuel, etc.) from other nations, 3.5 million barrels from Canada. That’s right, on net we import 3.5 million barrels of oil from Canada, use 1 million, and export the rest. The rest of the world we import as much as we export. As long as our Canadian supplies are secure we have no strategic interest in oil anywhere else in the world. Perhaps Europe does, then Europe can jolly well take on the role of preventing a war between Iran and Saudi Arabia. Frankly, its just not our problem. “But what if we get pulled into a war?” First, we shouldn’t unless we have an overriding strategic interest, and preventing Iranians from killing Saudis, while a noble goal, does not affect our national interest.
It’s time for us to evaluate our role in the world. We spend far too much of our resources fighting other nations wars for them. Personally I think that if Afghanistan can’t form a functional government in 18 years they probably won’t develop one as long as we are there. Europe is fully capable of providing its primary defense relying on the US only as an aid of last resort. Asia would regionally balance itself if the US slowly withdrew. We have no national interest in Africa, and since we import so little oil from the Middle East we have no interest there either. If we resized our military to be sufficient to “execute the laws of the union, suppress insurrections, and repel invasions” we would have a military less than half its current size.
We talk about scaling back the scope of government and draining the swamp. This is just one more area ripe for draining.