I believe Biden is directly responsible for the Ukraine invasion. If it was in the planning for 8 years, why did they do it when they did. It was a combination of believing (correctly) that Biden is weak and the fact that the slow down of drilling in the US reduced the world oil supply and made Europe dependent on Russian Oil. With Europe not able due to the need for oil, Putin believed he could walk right in. Fortunately his military was a whole lot weaker than he thought, along with a stronger resolve in Ukraine.