An excellent question. The long-term consequences are the realm of analysis, not politics, which is why I wrote this article. Those ideas shape how politicians make decisions and which issues to prioritize. To understand how your vote may impact foreign policy, study a candidate's knowledge, attitudes, and experiences of our relations with other countries. Specifically study their attitudes towards security guarantees, their language towards allied nations (especially the ones failing to meet their commitments to NATO), and how they respond to Russia's nuclear threats. If they are an incumbent, consider signing up for https://www.govtrack.us/ to get personalized updates about how your representatives vote on these matters.