 The territory was internally divided into two zones ruled by military governors - Muggia ended up in the northern Zone A ruled by Anglo-Americans, while the southern Zone B was ruled by the Yugoslav army.In 1954 the two zones were handed over to Italian and Yugoslav civilian governments and "de facto" annexed by the two countries in an arrangement finally formalized in the 1975 Treaty of Osimo, which established the former borders between Zones as the new Italy-Yugoslavia international border.Following the breakup of Yugoslavia in the early 1990s it formed the border between Italy and the newly independent Slovenia.