This is an example of using Diplomacy as a tool for foreign policy.
Diplomacy is the act of managaing international relations through various activities, including talks, forums etc.
Country's are often represented by 'Diplomats' who work on behalf of their country to ensure strong foriegn relations.
Some examples of diplomats can include counsel general, ambassadors etc.
In this example, the US is sending a format, government approved represenatives to another country in order to persudate them to adopt an environment protection policy that the US believes in. This is pure diplomacy at work where human to human interaction and goodwill is being used to create benefits for the United States.