The US has no God-given right to police the world. The choice between coups and supporting dictatorships is a false dichotomy.
You claimed that, except for during the Trump presidency, the US supports democracies and didn’t support dictatorships. Obviously, this is not true. It has supported dictatorships and continues to do so. It has even acted to replace democracies with dictatorships in the past. The US has no right to replace regimes, democratic or not, as it sees fit.
My point, which you appear to have completely missed, is that the US does in fact deploy its military to the borders of other countries. It constantly sends its aircraft carriers and warships to the Persian Gulf and the South China Sea. It has constructed about 750 military bases in over 80 countries, with the majority bordering countries that it has designated enemies. It even illegally occupies countries. I can assure you that those countries surrounded and occupied by US bases see this as a persistent threat. No country has been involved in more wars than the US throughout its short history.
Evidently, Russia finds NATO expansion throughout Eastern Europe and, in particular, on its borders with Ukraine to be a grave threat to its security. You have conveniently ignored the fact that the US shipped nuclear-armed or nuclear-capable weapons to Germany and Turkey amongst other countries during the Cold War. It also had a constant patrol of bombers armed with nuclear weapons circling Russia’s borders. But, it wouldn’t accept the USSR deploying nuclear weapons to Cuba. The US has a history of demanding from other countries what it wouldn’t accept for itself.