Russia and Ukraine

[Pat Mustard]

If he wants the regime to stick longer than a few days he'll need to occupy the whole country.  Fighting against a guerilla insurgency, especially in a foreign country, is really difficult plus the US and EU will keep that insurgency supplied for years.

They know how to do it, remember Afghanistan.

And this one will be even worse - Ukraine is MUCH better equipped to deal with an invader than Afghanistan was.

Boru

Look at history, pretty much everywhere shows that it's almost impossible for a foreign occupier to defeat a popular insurgency, from the Irish war of Independence (which my grandfather took part in, I've heard some stories), to the independence wars in south east Asia and Africa.