Generalizations
The concept of generalization was initially used for classes, but has been extended to other UML concepts such as actor and use case.
Examples of generalizations between actors:

The "Client" actor can have the USA or Export specialization.
To create a generalization between actors in a use case diagram:
button and drag the link from the specialized actor (eg: USA client) to the more general actor (eg: Client).The generalization then appears in the drawing.

When creating a second generalization, a dialog box allows you to reuse the existing generalization if it involves the same subject.