Two-level game theory is a political model, derived from game theory, that illustrates the domestic-international interactions between states. It was originally, introduced in 1988 by Robert D. Putnam, in his publication "Diplomacy and Domestic Politics: The Logic of Two-Level Games".[1]
Putnam had been involved in research around the G7 summits between 1976 and 1979. However, at the fourth summit, held in Bonn in 1978, he observed a qualitative shift in how the negotiations worked. He noted that attending countries agreed to adopt policies in contrast to what they might have in the absence of their international counterparts. However, the agreement was only viable due to strong domestic influence - within each international government - in favour of implementing the agreement internationally. This culminated in international policy co-ordination as a result of the entanglement of international and domestic agendas.[1]