I'll tell you. Nothing. They are going to do nothing. Because they can't.
Life is good.
But with Venezuela's +300bn oil barrels at Trump's disposal now, I bet the gas prices will plummeted. I wonder how the MAGA fanbase will react (probably will be happy to let just this one "nation building" project to slip through their ethics).
Most Americans can't find Venezuela on a map. (Presumably most humans can't)
They'll overlook this (and similar moves) and pay attention to domestic policy, unless we're dragged into an extended war.
Putin and Kim will -not- be emboldened by this act - quite the opposite.
International politics is anarchy. Rules are enforced by the hegemon.
International law exists - it’s the very purpose of the International Court of Justice