http://travel.state.gov/travel/cis_pa_tw/cis/cis_980.html

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Travelers occasionally report immigration difficulties with
Chinese authorities when crossing the Nepal-China border over land in
either direction. There have been reports of travelers being detained
and subsequently deported by the Chinese authorities for possessing
items deemed to have incited anti-Chinese rhetoric. Chinese authorities
often require American and other foreign tourists to organize "group"
tours through established travel agencies as a prerequisite for
obtaining visas and entry permits into Tibet. U.S. citizens planning to
travel to Tibet from Nepal may contact the U.S. Embassy in Kathmandu
for current information on the status of the border-crossing points.
Travelers may also wish to check with the Embassy of the People’s
Republic of China in Nepal for current regulations on entry into Tibet.

HIV/AIDS restrictions: The U.S. Department of State is unaware of any HIV/AIDS entry restrictions for visitors to or foreign
residents of Nepal.

Information about dual nationality and the prevention of international child abduction can be found on our web site. For further information about customs regulations, please read our Customs Information Sheet.

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