"The “security dilemma” is a central concept in the academic study of international politics and foreign policy. First coined by John Herz in 1950 and subsequently analyzed in detail by such scholars as Robert Jervis, Charles Glaser, and others, the security dilemma describes how the actions that one state takes to make itself more secure—building armaments, putting military forces on alert, forming new alliances—tend to make other states less secure and lead them to respond in kind. The result is a tightening spiral of hostility that leaves neither side better off than before.
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Consider this recent propaganda video tweeted out from NATO headquarters, responding to assorted Russian “myths” about the alliance. The video points out that NATO is a purely defensive alliance and says it harbors no aggressive designs against Russia. These assurances might be factually correct, but the security dilemma explains why Russia isn’t likely to take them at face value and might have valid reasons to regard NATO’s eastward expansion as threatening.

Adding new members to NATO may have made some of these states more secure (which is why they wanted to join), but it should be obvious why Russia might not see it this way and that it might do various objectionable things in response (like seizing Crimea or invading Ukraine). NATO officials might regard Russia’s fears as fanciful or as “myths,” but that hardly means that they are completely absurd or that Russians don’t genuinely believe them. Remarkably, plenty of smart, well-educated Westerners—including some prominent former diplomats—cannot seem to grasp that their benevolent intentions are not transparently obvious to others.
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The same dynamic is operating in Asia. Not surprisingly, China regards America’s long position of regional influence—and especially its network of military bases and its naval and air presence—as a potential threat. As it has grown wealthier, Beijing has quite understandably used some of that wealth to build military forces that can challenge the U.S. position. (Ironically, the George W. Bush administration once tried to tell China that pursuing greater military strength was an “outdated path” that would “hamper its own pursuit of national greatness,” even as Washington’s own military spending soared.)

In recent years, China has sought to alter the existing status quo in several areas. As should surprise no one, these actions have made some of China’s neighbors less secure, and they have responded by moving closer together politically, renewing ties with the United States, and building up their own military forces, leading Beijing to accuse Washington of a well-orchestrated effort to “contain” it and of trying keep China permanently vulnerable.

In all these cases, each side’s efforts to deal with what it regards as a potential security problem merely reinforced the other side’s own security fears, thereby triggering a response that strengthened the former’s original concerns. Each side sees what it is doing as purely defensive reaction to the other side’s behavior, and identifying “who started it” soon becomes effectively impossible."

https://foreignpolicy.com/2022/07/26/misperception-security-dilemma-ir-theory-russia-ukraine/

The Security Dilemma also explains why balance of power will not end well.