starpvalstu

From starp (“between”) +‎ valstu (“state[gen.]”).

starpvalstu (invariable)

1. interstate (that which exists or happens between or among independent states; international)

   starpvalstu attiecības ― interstate, international relations

   starpvalstu sakari ― interstate, international (telephone) calls

English “interstate” more often than not refers to states in a federation, like the United States (e.g., an interstate highway). Latvian starpvalstu can also be used in this sense, but more often than not it refers to independent states or countries, thus being rather equivalent to English international or multinational.