There are a number of things the current United States administration is doing that we need to carefully consider. Many of these things have a potential for long-term adverse consequences that appear to be a result of either an indifference to or misunderstanding of the lessons of the Twentieth Century.
Probably the clearest example of this indifference/misunderstanding is the cavalier way Mr. Trump sticks his fingers in the eyes' of leaders of European countries. There was no reason for him to treat the head of Germany like she had a serious communicable disease. He was in the Oval Office with Chancellor Merkel. Photographers wanted a hand shake shot. Trump refused. That was the most obvious, but not the only way he has blown off European leaders. You have to question whether he understands anything about the century of history he seems intent on just throwing away.
Prior to World War I, the U.S. was pretty isolationist, which is why it was nearly three years after WWI started before American troops became involved. Europe was 3000 miles away and was not our problem. Then in 1914 came "The Guns of August". The war was started when some anarchists murdered an Austrian Arch Duke in Sarajevo. Serbia rejected an Austrian demand that the anarchists be turned over to them, Austria decided to invade Serbia to get them, and Europe blew up in a blood bath. Five years later 18,000,000 people had been killed; another 20,000,000 people had been injured; and Russia (which was far and away, the biggest country in Europe) had fallen into the hands of a doctrinaire oligarchy that quickly morphed into a murderous dictatorship.
At the end of the war, in 1919, the victors imposed The Treaty of Versailles on the losers, including Germany. Also in 1919, English economist, John Maynard Keynes, published his book, "The Economic Consequences of the Peace," in which he argued that the treaty was far too onerous. Keynes predicted that the German economy would collapse under the burden, the German people would, in desperation turn to a strong dictator, and the war would resume. Sure enough, by 1939, Hitler had risen to a position of absolute power, invaded Poland, and resumed the war, now called WWII.
Russia formed the Union of Soviet Socialist Republics (USSR) prior to WWII, and had taken over several other countries and made them part of the USSR. As WWII ended, Stalin made a huge land grab so that by the end of the war, Russia had about half of Germany and all of Eastern Europe in its clutches. Fortunately, the Allies learned from their mistakes, and adopted The Marshall Plan to help Western Europe rebuild and recover from the devastation created by the War.
At the same time, Western leaders had come to regard Stalin as the vicious murderer he had become. Reports came out of Moscow of mass executions of Stalin's perceived political enemies. Those who were not simply executed were banished to slave labor camps in Siberia. Then, in 1949, The USSR detonated an atom bomb.
NATO was formed in 1949 as an alliance of the United States and Western European countries specifically to keep Russia in check and prevent it from grabbing and enslaving any more of Europe and its citizens. Stalin's regime was brutal. Millions of perceived political enemies were either murdered or sent to die performing slave labor in Siberia. The KGB was a major administrator of death to the citizens of Russia and the countries seized by Russia. Vladimir Putin, the current President of Russia, was a fair-haired boy rapidly advancing in the KGB after joining it in 1975. Since becoming president, Putin has demonstrated a serious intent to expand Russia into the old Soviet Union. He annexed Crimea from the Ukraine in 2014, and has been indiscriminately bombing civilians in Syria in support of a bloodthirsty dictator there.
One of the primary objectives of the United States in helping to form NATO was to see to it that if any battles had to be fought, they would not be fought on American soil. Selfish, I know, but all you need to do is look at pictures from the South after the Civil War to see the wisdom of this idea. And they did not have airplanes with rockets and bombs in the Civil War. We have spent a lot of money on NATO, but it pales in comparison to what it would cost in blood and treasure to fight a modern war here. Our NATO allies have taken huge risks because they have allowed us to put soldiers and arms on the ground in their countries. If we wind up in a shooting war with Russia, the earliest casualties will be in the parts of the NATO countries where we have been allowed to create Russia controls.
Withdrawing from NATO would result in simply throwing away all of that blood, sweat and tears. The "Greatest Generation" defeated Germany, defeated Japan and corralled Russia. Why Mr. Trump wants to hand such a gift to Putin is a complete mystery. It is either incompetence, indifference or corruption. It certainly is not putting America first.