NATO no longer serves US national interests. Possibly it never did. During the Cold War NATO supposedly balanced a forces from the Warsaw Pact and kept Western Europe safe. The Cold War ended almost 30 years ago. In reality Russia has not wanted to invade Europe since Trotsky. Currently the eastward expansion of NATO is severely straining US-RUSSIA relations. It is insane for the USA risk thermonuclear Armageddon for the sake of Lativia, for example...Russia does not want to invade the West. European problems should be dealt with by Europeans. Continuing our involvement NATO only provokes Russia and actually makes us less safe. How would Americans feel if Latin America formed a Treaty organization with Russia called LATO and Russian troops were based on the Rio Grande?
NATO was created due to the threat of an expanding Soviet Union and its communist neighbours. The Soviet Union created their own version of NATO - called the Warsaw Pact in retaliation. However, since the fall of the Soviet Union, the Warsaw Pact has been dissolved. Now there is only NATO, despite no Warsaw Pact and no Soviet Union. Further, despite agreements between Reagan (US) and Gorbachev (USSR) to not have NATO expand beyond Germany, it is still expanding to this day. Appeasement does not work. NATO will keep expanding. While Russia is far from being an angel, they too act in their national interest (just as the US does). Russia sees an expanding NATO and seeks to build up its military in retaliation. Without NATO creeping closer and closer to Russia's border, the US and Russia could be allies.