The article says the U.S. and NATO broke promises and expanded east toward Russia. This expansion and NATO moves toward Ukraine made Russia feel threatened. Russia invaded Ukraine in 2022, which the authors blame on NATO and U.S. failures.
ORIGINAL LINK: https://armedforces.press/the-graveyards-of-ukraine-another-case-study-in-u-s-political-and-military-incompetence-part-i-of-ii/