Cultural exchanges between enemies. The term came from a trip taken by the US table tennis team to Mao's China, back in the days before official relations. The practice goes back further: there were one-off US/USSR sporting events staged as far back as Stalin/Red Scare days, and cultural analogues, like Bolshoi tours. In recent decades, there has been "baseball diplomacy" between the US and Cuba, and ROVA's "Saxophone Diplomacy", a pre-glasnost Soviet tour.