Later, in a comparative analysis of 20 countries (industrial and developing) Wils, Kamiya and Choucri (1998) extended the analysis of internal sources of international conflict, and examined the nature of the feedback effects, namely how international conflict in turn influences and even alters the master variables of the state and changes the internal sources of conflict as well as propensities for particular modes of external behavior. Subsequently, Lofdahl (2002) modeled the relationship between internal dynamics of growth and development rooted in the master variables, on the one hand, and propensities toward particular patterns of international trade and their environmental impacts, on the other.