truth=facts. facts are objective. it’s a fact that the USA is a country in north America. there is no disputing that.

Not trying to say that everything is subjective, but that in particular is kind of a bad example.

Countries are socially constructed. The US is something that only exists so long as people agree that it does. There is no objective, material way of determining where one country ends and another begins.

In fact, there was quite a bit of disputing that historically. Prior to the American Civil War, lots of people said that the US was not a country but a union between countries, they were called "states" after all, and it was common to say "The United States are" rather than "The United States is." There are still successionists today who argue for that interpretation. To say that the US is objectively a country means that there must be something in material reality that we can point to to prove that one interpretation is correct and the other is incorrect. What is that thing?

Whatever that thing is would have significant implications for how we see the world and look at other disputes, whether we're talking about Spain and Barcelona, the UK and Scotland, China and Tibet, or Israel and Palestine. For example, if you say that historically, most US secessionists supported slavery and therefore they lacked moral character and the position is illegitimate, then it follows that what states exist is a function of the moral character of their supporters, and that seems to be adding lots of assumptions and moving away from any sense of objectivity.

"The US exists" is much more subjective than something like "This chair exists." With the latter, you could argue that grouping a collection of atoms into the category of "chair" is arbitrary and there's no way of determining when an atom stops being a part of "chair," but that's much more pedantic than socially constructed concepts that don't really have a physical essence.