The documents, published Monday in collaboration with Japanese news broadcaster NHK, reveal the complicated relationship the NSA has maintained with Japan over a period of more than six decades. Japan has allowed NSA to maintain at least three bases on its territory and contributed more than half a billion dollars to help finance the NSA’s facilities and operations. In return, NSA has kitted out Japanese spies with powerful surveillance tools and shared intelligence with them. However, there is a duplicitous dimension to the partnership. While the NSA has maintained friendly ties with its Japanese counterparts and benefited from their financial generosity, at the same time it has secretly spied on Japanese officials and institutions.