The US doesn't need to annex any country, they just pay their "partners" overseas, or, if they go "rogue", a few US navy ships show up and that's it.
BTW, you are forgetting more recent events in which the US govt. has been involved, directly or indirectly:
Iraq (war)
Afghanistan (war)
Syria (war)
Libya (war)
Honduras (coup d'etat)
Brazil (soft coup d'etat)
Paraguay (soft coup d'etat)
Venezuela (economic blockade)
Mali (war)