WTF? A nation state couldn’t have seized the assets? It seems that multinational megacorps are truly more powerful than and above the law in small countries these days.
The backstory here is, Chevron used to have a lot of assets in Ecuador as part of a joint venture with the Ecuador state oil company. The joint venture wound up, Chevron left, and now there's some dispute over whether any remaining clean-up is properly the responsibility of Chevron or Ecuador. But this is being discussed after they closed everything down, sold up, and left.
All that's left if for Ecuador to go try and convince the legal system of other countries (where Chevron does have assets) to do something. And so far, that's not working very well for them.
They can send much nastier things too. When you get to state-level actions, the law, or at least the repercussions for breaking it gets a lot iffier.
Why in small countries? They do what they want in America too.