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Oh shit. It really is the empire.
According to http://www.techvisas.com/taxation.htm
Taxation of Aliens who Have Departed - Anti-Expatriation
Rules.
Aliens who live in the U.S. as residents, irrespective of
visa status, face special anti-expatriation rules. Such
rules were formerly applied only to U.S. citizens who
cancelled their U.S. citizenship in order to be free of
U.S. gift and estate taxes. As a result, termination of
lawful permanent resident status after several years will
result in continuing liability of the foreigners gifts
and patrimony (assets) to U.S. probate and estate taxes
for 10 years after such termination
