Can you guess which 2 states make up half of global military expenditure?

I recommend that you all read this book by Ian Morris: “War! What is it good for? Conflict and the Progress of Civilization from Primates to Robots”. It provides a very long-term view of the role of war in the progress of civilization, where “progress” in this context means the reduced likelihood of dying by violent means. The end of the book is about the likely consequences of the trend where China’s military power rivals that of the USA (assuming thousands of years of human history has anything to teach us).