There is no such thing as an "international copyright" that will automatically protect an author's works in countries around the world. Instead, copyright protection is “territorial” in nature, which means that copyright protection depends on the national laws where protection is sought. However, most countries are members of the Berne Convention on the Protection of Literary and Artistic Works and/or the Universal Copyright Convention, the two leading international copyright agreements, which provide important protections for foreign authors.
Under these treaties, a qualifying work foreign work generally must receive the same protection as a local work. This bedrock principle of international copyright law is called “national treatment.” International copyright agreements also set forth certain “minimum standards” of copyright protection. For example, the duration of copyright generally lasts for a minimum period of life of the author plus 50 years. The United States also maintains copyright relations on a country-by-country basis. For further information and a list of countries that maintain copyright relations with the United States, see “Circular 38a, International Copyright Relations of the United States”.
The information used on this page came from the USPTO
https://www.uspto.gov/learning-and-resources/ip-policy/copyright/copyright-basics