First off, I don't see that Trump has urged abandonment of NATO. Trump made a comment that the U.S. for decades has been paying a disproportionate amount of the cost of NATO, and that only 5 nations in NATO have been paying their agreed-to share of the military cost of NATO. Trump did not call for the disbandment of NATO, he said that the U.S. has a huge public debt and is not flush with cash the way we were decades ago, and therefore we should put pressure on other NATO nations to pay what they agreed to pay, and ONLY UNDER THOSE CIRCUMSTANCES, where they are not doing their part, did Trump say the U.S. should use the threat reciprocally not honoring its commitments unless other nations honor theirs with us.
Second, as hardline a Reagan conservative as Pat Buchanan said much the same things in his 2007 book Day of Reckoning, that the U.S. missed an opportunity after 1991 to make a peaceful ally of Russia, missed by expanding NATO into former Warsaw Pact nations, and into nations of the former Soviet Union itself! Missed by not respecting Russia's sphere of influence.
Buchanan said that this was inherently threatening to Russia, and it invaded their sphere of influence in an intolerable (to them) way. Just as the U.S. would be enraged and hostile if Russia similarly intervened in, say, Mexico or Canada on our border. That we should respect their sphere of influence.
Buchanan also said we should have, after 1991, re-negotiated or completely scrapped our NATO, SEATO, and other mutual defense pacts, as they became outdated at the end of the Cold War. That from that point forward, we should have the option to intervene if it is the smart thing to do, but not be obligated to be engaged in a war by an obsolete treaty, when there is no longer a global communist threat.
Also, we have no infrastructure to fight a war in Ukraine or former-Soviet Georgia, and therefore we have no business making NATO or other pacts with these nations, any more than Britain had any business offering a war guarranty to Poland in 1939. A war guarranty that unnecessarily began World War II, that in the absence of the guarranty, Poland would have negotiated with Germany. (Germany had for months wanted only to build highway and rail over the Polish Corridor to connect Germany with the separated East Prussia, wanted only the city of Danzig that was 95% German, and would have left the remaining 1.2 million Germans in the Corridor as citizens of Polaand. Hitler actually envisioned Poland as a potential ally to help him invade Russia. Russia was to sole obsession of Hitler, and if Britain and France had not declared war on him, Hitler would have focused all his energy on Russia, and not invaded Denmark, Norway, Netherlands, Belgium and France. If Britain and France has simply stood in the sidelines and let Germany and Russia go after each other, they would still have their empires intact. )
In the U.S., conservatives generally have an isolationist view that the U.S. should maintain a large military as a deterrant to enemy expansionism, but not use it unnecessarily, or be contractually obligated to go to war (as in say, Georgia in 2008) when the state in question has acted in a way that is arguably provocative to Russia, and an escalation is unnecessary.
I fully believe the U.S. (1) should (and should have 2 years ago!) provide arms to the Ukranians so they can deter Russian invasion and defend themselves, and (2) should prepare reserves of U.S. oil and natural gas for potential transport to Poland, Germany and the rest of Europe, so that Russian threats to cut off energy to these nations ceases to be leverage to cow them into submission.
Soft power, vs. hot war.
Hillary Clinton is more of an interventionist, as are the disempowered neo-con wing of the Republicans.
