What's Putin's Strategy?

As President Putin again threatens Ukraine, the world is asking what's his wider foreign policy strategy? Can the west stop him in his tracks, and if it can't, will that show weakness, emboldening not only Putin but also other autocrats like China's President Xi? In fact, is the west now facing a dangerous, de facto alliance of Russia and China - and if so, how best does it respond to this dual threat to global stability?