How does the realist theory of international relations in the article “structural realism” by John Mearsheimer answer the question of what causes war between two states?

"Structural Realism" is an article written by John J. Mearsheimer.
In the article, Mearsheimer posits that structural realist theory does not quantify cultural differences or government regime types between nations. Mearsheimer argues that the international system gives all nations the same incentives to gain more power, disregarding whether those nations have a democratic government or an authoritarian one.
Mearsheimer argued that, in structural realist theory, nations are not always pushed toward war because of survival, or because of a "kill or be killed" mentality. Mearsheimer states that "security is not always the principle driving force behind a state’s decision for war. Ideology or economic considerations are sometimes paramount." He cited Germany's motivation during World War I as an example.
Some structural realist theorists believe that nations that increase their military and geopolitical power eventually leads to self-destruction, as in the case of Nazi Germany and Imperial Japan, who initiated World War II but ended up being defeated with their respective economies and global political powers decimated.
Realist theorists believe that modern-day China's rise in economic power will also lead to increased military might, and that this will cause instability in the Asia-Pacific region, and in the international system as a whole. They theorize that China's Asian neighbors and the United States could react in irrational ways to China's increased military power, and which could lead to warfare or, at the very least, diplomatic conflicts.
https://www.mearsheimer.com/