20 CFR §1002.34

1. (a)USERRA applies to all public and private employers in the United States, regardless of size. For example, an employer with only one employee is covered for purposes of the Act.
2. (b)USERRA applies to foreign employers doing business in the United States. A foreign employer that has a physical location or branch in the United States (including U.S. territories and possessions) must comply with USERRA for any of its employees who are employed in the United States.
3. (c)An American company operating either directly or through an entity under its control in a foreign country must also comply with USERRA for all its foreign operations, unless compliance would violate the law of the foreign country in which the workplace is located.