Federal registration is not valid outside the United States. However, if you are a qualified owner of a trademark application pending before the USPTO, or of a registration issued by the USPTO, you may seek registration in any of the countries that have joined the Madrid Protocol by filing a single application, called an “international application,” with the International Bureau of the World Property Intellectual Organization, through a site such as PatentExpress.com.
Also, certain countries recognize a United States registration as a basis for filing an application to register a mark in those countries under international treaties. See this link for further information. The laws of each country regarding registration must be consulted.