The first sale doctrine, also known as patent exhaustion, applies internationally as established by certain jurisdictions like the U.S. Supreme Court. Once a patented item is sold abroad by the patent holder or with their consent, they cannot enforce their U.S. patent rights to restrict its importation or subsequent sale within the U.S.
For example: If a smartphone patented in the United States is sold by the manufacturer in Europe, they cannot sue European buyers who then sell the phone in the U.S., because their patent rights were exhausted at the point of sale in Europe.