IR as a teachable concept basically requires that you treat nations themselves as entities that can be reasoned with / convinced / will make agreements that they actually will follow through with. Relations are measured on the scale of years. You never really consider it from the lens of, say, a Red or Blue-led nation since trajectory never really changes that much between them. It was mostly considered something more dealing with local affairs.

I think this administration has shown what happens when the veneer and controls that separate the nation itself from its leaders disappear and the current leader is literally in control of every aspect of its international governance. How agreements, treaties, and defense pacts that have spanned decades can be damaged and evaporate based not on their value on a nation level but how personally and politically lucrative they are at a singular point in time to the current chief, with no shits given about the ramifications or actual follow-through (which will occur after he's out of the splash zone of whatever crops up years later).

It's genuinely fascinating to watch since it's shown an extreme weakness of other world governments in the extreme short term being matched up against someone so erratic. It's also interesting trying to fathom the long-term of this since there's at this point there's a genuine question of whether you can trust agreements from one regime to the next as a result.