I'm going to be as brief as possible because you're a foreigner with limited knowledge of US politics, limited interest in what's best for the US as opposed to Canada or other foreign countries, and because of my preference for a simple literary style due to the nature of this forum and the arthritis in my hands. But as I do have some respect for your intelligence I'll give it one brief whirl.
There are four easily identifiable blocs on the US foreign policy right.
- libertarians - not numerous, but among the intelligentsia
- old-right isolationists, a.k.a. paleocons - often join with libertarians in non-interventionism
- traditional hawks - numerous, not limited to military, veterans, law-enforcement
- neocons - take hawkishness to the extreme, but are not numerous outside the Beltway. Powerful and preeminent in foreign policy for the last quarter century. These folks are most threatened by and hostile to the Trump phenomenon.
Scattered among the the first three of these groups are the realists. Realists see the world as it is - the Bismarckian "art of the possible". Cynical and world-weary, they don't have permanent attachments, but do have permanent interests.
The bulk of Trump supporters have grown weary of endless foreign war. As isolationists and traditional hawks, their votes have prevailed in the Republican primaries. This is Trump's constituency coming together and becoming organized and now speaking with a bellowing megaphone, the nationalist-populist prairie fire.
"Personnel is policy". Should Trump be elected,he will likely try to stock his administration with foreign policy realists.
Trump knows Bush drove us into a ditch in Iraq. Beyond a few advisors, he will not send troops to the middle east.
Obama has continued Bush's policies, dropping the messianism but keeping the alliances and commitments, reducing defense spending and added climate change. We have a policy of containment of Russia, China, ISIS/al Qaeda and the CO2 molecule, together with a slew of commitments to defense treaties with other countries, the rights of various groups and endangered species. Together, not sustainable.
The US has ~4% of the world population and ~20% of the GDP. We cannot continue to police the world. Trump will rethink US commitments to feckless, faithless allies. He will not risk nuclear war over the Spratleys or eastern Ukraine. Trump realizes the big powers must be dealt with as authoritarians with their own interests. He will deal with Russia and China as legitimate powers, not rogue states to be subdued by us. He will likely end the war in Afghanistan by making a deal with the Taliban in Pakistan, and the war in Syria by partition.
Trump is an instinctive dealmaker. He will build rapport with world leaders and not be a hot blooded unilateralist interventionist like Bush or a dithering multilateralist like Obama. Trump's leadership will be the strengthening of the economy. He will join realism with economic nationalism. He may seek to reprise the multipolar system of Nixon and Kissinger.
To his critics who see him as buffoonish and impetuous, Trump supporters may ask, "When has the conventional wisdom proved correct?"
If he does succeed to the presidency, Trump will have proved himself a strategic thinker and not a dummy.