By analyzing bilateral cooperation involving civilian nuclear technology from 2000 to 2015, this study finds potential proliferation uncertainty in recent technological nuclear cooperation. We use the dataset that divides technological nuclear cooperation into two categories -concrete and supportive, where concrete cooperation involves the more in-depth transfer of technology related to nuclear power and fuel cycle than supportive cooperation. We employ multinomial regression analysis to investigate what economic, political, military, and non-proliferation considerations enable more concrete nuclear cooperation. Our empirical results suggest that potential proliferation uncertainty exists in concrete cooperation. While concrete nuclear cooperation, in general, requires compliance with non-proliferation norms more strictly than supportive cooperation, examining military factors together with the compliance to the non-proliferation norms shows some concerns. Specifically, we find that suppliers of concrete nuclear cooperation have overlooked weak compliance with some non-proliferation norms when there exist common military interests. We also show that client countries with high military expenditure are more likely to engage in more concrete nuclear cooperation. Lastly, we find that supplier and client countries tend to complement their weak military alliance with more concrete nuclear cooperation. The findings underscore the responsibility of major suppliers and the international community for nuclear nonproliferation.