Effective March 5, 2008, ICAO Personnel Licensing standards require that
all pilots with commercial, ATP or FE certificates operating
internationally as required crewmembers of an airplane have an airman
certificate with an endorsement of language proficiency. In the case of
persons holding a U.S. airman certificate, the language proficiency
endorsement will state "English Proficient."

Here's the link.

https://amsrvs.registry.faa.gov/amsrvs/Logon.asp

Do you need to have the new license flying in the US? (Domestic) I don't fly domestic but I have a buddy who does...