The founding of what is now the EU, largely at the time driven by the recoil from two terrible wars, was a good example of learning from history. Countries which are democracies, which abide by human rights standards and which adhere to the rule of law seldom have appetites for warring among themselves. Unfortunately, it doesn't stop them from interfering in countries which don't necessarily share those standards and it doesn't stop them from indulging in the kinds of proxy wars we saw in Central America in Reagan's time or in the running sore of Middle East conflicts. Generally, you just have to look for who it is that the West is arming. The lesson of Vietnam wasn't well learned.