Before you draw back your outer lines of defense, you beef up and integrate your inner lines.
The Red Sea situation is proving that the US can no longer secure the world's traffic lanes. BRICS momentum and reality of regional powers like Russia, China, and Iran are challenging US power and dollar dominance. I think Trump wants to abandon or de-emphasize NATO. It's a net liability to the US and the western vassals are likely to crack up (at least their "garden" mentality will crack, as their quality of life drops). They can go fight russia on their own, tough guys that always under-funded NATO anyway.
On all of these territorial ideas, I'm very prejudiced against use of force to accomplish their annexation. We have a bad enough reputation. I don't know much about procedure for this stuff, but how we do it is important.
On Greenland, I'm all for it, given their people welcome it and are not forced in. The trade routes and the resources are self-evident. Russia opening up more traffic across the arctic ice cap, combined with China's maritime commercial power, make the issue more urgent. I don't know the effect this will have on Congress, other than to say that it will become a hyper-Wyoming (small-population state with 2 senators and 1 rep, hence heavy Senatorial importance). Maybe keep as a province, until they prove they aren't lefites.
On Panama, sure, though I see it as more likely to lead to open conflict. If the Panamanian population isn't for it, we'll forever be seen as the invading occupier.
On Canada, maybe only Alberta, Saskatchewan, Yukon, NW Territory, and Nunavut. The rest/Leftie Canada will flip the Congress as blue as California. I've heard enough snooty Canadians run down Alberta. I know I like those people.
On Mexico, just build the wall, maybe some more moats, some interlocking fire fans, and finally exert control. Cross border punitive raids against cartels are a mess we make for ourselves.
Done well, America is fair and working in her regional interest. Done wrong, ROW will hate us. We need the newly annexed populations to be proud, loyal Americans and to welcome it. That won't happen by force.
I suspect a heavy round of foreign base closures. The Russia/China/Iran axis is shoring up their regional power and we are over-exposed to other people's inability to make nice with their neighbors. I wonder if this is a muscle-flex before Trump drops the embarrassing news that the US is closing XX bases worldwide. Reality eventually hits everyone - even the mighty. Some dreaming by me on that.