Since around 2018, Chinese experts have concluded that Washington’s nuclear posture now poses increasing challenges to China’s deterrent. In particular, they have been concerned about shifts in U.S. strategy outlined in the Pentagon’s 2018 Nuclear Posture Review. Many Chinese experts have noted that the review highlighted China as a strategic competitor and that it argued for lowering the threshold for the use of nuclear weapons, including in response to certain kinds of nonnuclear attacks. They also noted the report’s emphasis on low-yield nuclear weapons, which could possibly be used to coerce China. Citing the views of analysts such as Elbridge Colby, who served as deputy assistant secretary of defense for strategy and force development in the Trump administration, Chinese experts saw the new U.S. posture as designed, in part, to compensate for the fact that East Asia’s conventional military balance was shifting in China’s favor.
Is there any international law that prohibits the use of nuclear weapon against another country? Considering that the U.S. lowered the threshold for the use of nuclear weapons, including in response to certain kinds of nonnuclear attacks, it makes me wonder if there's any law that prohibits the use of nuclear weapon against another country, and if the consequences of using nuclear weapons is rather low for countries, especially powerful ones.