This paper examines the main defense activities between China and Russia since 2014 that led to the growing ties between Chinese and Russian militaries, manifested by increasing arms trade, technology transfer, and bilateral military exercises. Closer cooperation has resulted in deeper integration of the two armies into a common defense space, paving the way for a quasi-military union between Russia and China in the future, as the two countries’ threat perceptions have worsened. Their continued military and defense collaboration and shared interests in a less-American order will have far-reaching implications for the security architectures in both Asia–Pacific and Eastern Europe.