Is government a physical object?
I imagine the 5 aggregates happening within a frame, which is a different one for every living creature.
Governments can shape "actions of the country", but in the physical sense there are no such objects like "government" or "state".
There is this frame, this perspective, which is unique for any of us, starts at birth, and ends at death. The five aggregates can only be experienced through that perspective.
Even a point of view of a government isn't so definite and unified; so "can only be experienced through that perspective" is just an idea.
I can't feel what my cat is feeling when I touch it, I can only experience the aggregates appearing inside my perspective, not the one of the cat.
Imagine a beam of sunlight coming to an otherwise dark room. Depending on the time of the day and of the time of the year, direct light falls on particular parts of the room.
All that depends on the position of the sun, and the position, the form and the size of the window, and of the glass quality etc. Suppose you experience what goes on in that room. Should you identify with the window?
I don't feel like this is contradicting any buddhist view. The problem is that I don't see how one is suppose not to identify with his own perspective.
The Buddha spoke of "his" thoughts and actions, like "I did this, I do that".
But he didn't believe that this "I" was a kind of real object.
Just like we say "government did this and that", but that is just a summary on activities of various temporary executives who happen to come together for a while.
1) Where is the impermanence in this ?
All the governments change, sooner or later, and countries cease to exist.
2) How can identifying a self there can lead to suffering ?
If we believe in "I" and "my things", we feel much fear and suffering when they are going to be lost.
Think of how much arguments and wars happen due to constructs based on such beliefs.
Stealing, robbing, murders, suicides - where do they come from?
3) Is there a reference about it in the suttas ?
Practically all the Buddha's teaching speaks about this - how processes create "self", and "self"-based processes develop suffering.
See my explanations of Twelve nidanas.
Also in the "Cittamatra school" (Only Consciousness) see the model of 8 consciousnesses, where the seventh seems to be like the window between the first six and the unlimited alaya-vijnana.