The Central American countries are also becoming increasingly dependent on the United States, despite the fact that they are receiving less United States economic aid. The cause of instability and backwardness in Central America continues to be a highly exclusive and concentrated socioeconomic structure subordinated to foreign interests, chiefly those of the United States. Latin America runs the risk of remaining on the sidelines of the present world economic dynamic. The war on drugs thus represents one more burden for the countries of Latin America. Mexico's political and diplomatic activism in Central America began with the government's support for the Torrijos-Carter Treaties, signed in September 1977, and above all, its backing for the Nicaraguan Revolution. The economic aspect of Central American-Mexican-United States relations is dominated by one theme of strategic importance: the possibility of a North American common market composed of Mexico, the United States, and Canada.