JoeF said:
If you have never been back to that other country, then why do you keep being a permanent resident there?
That's really a question to be asked of that third country, now then isn't it?
Keeping that indicates that you still consider yourself a permanent resident of that country.
No, it merely indicates that this third country considers me still eligible to reside their permanently. It says nothing about what I consider myself. If anything, since I obtained US permanent residency and reside here, I consider myself a US permanent resident.
As far as I see it, maintenance of US permanent residency is a question of my actions and USCIS. I am not under any obligition to actively renounce any other permanent residency statuses I may have - I just need to conduct myself as though I reside in the United States. That may or may not (usually will) cause me to lose permanent resident status elsewhere.
Hypothetically, let's say that my Imperial Grand Potentate loosened its requirements for permanent residency, to the point where it truly was
permanent. As a gesture of my magnificence and generosity, you could never lose your permanent residency status.
Does that mean that the beneficiaries of my gift could never become US permanent residents, and that I had veto power over wether they could immigrate to the US? Of course not.
There is a long-established principle in US law that the US will generally ignore other nations' actions. This is especially true in terms of naturalization; while the oath requires you to renounce all allegiances to other states, the US makes no requirement that you actively renounce your other citizenships. Under Canadian law, my renunciation carries no legal weight, and Canada still considers me a citizen. Does that make my naturalization invalid? Of course not.
As I said, the US authorities can not know about whatever laws the other country has that allow you to not going there in years, and they have no indication if and when that other country's laws change. All they can do is go from the fact that you are a permanent resident of another country.
No, all they can go on are my actions and conduct, like they do in any other fact of immigration law.
And, in consequence, if your stay in the US is temporary (since you are a PR in another country), you can not be a PR in the US.
How can a third country decide that my stay in the US is temporary, any more than you can decide about the permanence of my stay?