An explanation of U.S. Patent Law. This information is from "A Basic Guide to Exporting" provided by the U.S. Commercial Service to assist U.S. companies with exporting.
Last Published: 10/20/2016
U.S. patent law now allows a patent to be granted to the first inventor to file a patent application. (Patent applications filed before March 16, 2013 will be subject to the old first-to-invent rules.) U.S. patent law grants a patent to the first inventor. The U.S. provides a 1-year grace period that does not preclude an inventor from obtaining protection after an act that would make the invention public, such as publishing, offering for sale, or use of the invention within the 1-year grace period. 

Many countries, including most European countries, lack a grace period that allows an inventor to so disclose an invention before filing a patent application. In countries with an absolute novelty rule, the inventor must file a patent application before making the invention public anywhere. Hence, even the publication of an invention in a U.S. patent grant is a disclosure that can defeat the right to obtain foreign patents unless the applicant is entitled to claim the right of priority under the Paris Convention. The America Invents Act (AIA) of 2011 measures the one-year U.S. grace period from the claimed foreign priority date.

This means that if an applicant is entitled to a foreign priority, the U.S. filing date for an application’s claimed invention can now include the earlier, international application filing date.
Because the United States handles protections differently from most other countries,things you take for granted here in the U.S. might not be the same when you export.

Many countries require that an invention be worked locally to retain the benefit of the patent. Working a patent may require manufacture of the patented goods within the country, or it may be met by importation of goods covered by the patent, depending on the law of a particular country.

For an invention made in the United States, U.S. law prohibits filing abroad without a foreign filing license from the U.S. Patent and Trademark Office unless 6 months have lapsed since a U.S. application was filed. This prohibition protects against transfers of information that might damage U.S. national security. The penalties for filing abroad without following these requirements range from loss of U.S. patent rights to possible imprisonment (if classified information is released). In addition, other export control laws require you to obtain a license before exporting certain technologies, even if no patent application is filed—or the laws may bar the technologies’ export. Because the U.S. handles protections differently from some other countries, practices you take for granted at home might not be the same in your export markets.