Before realizing that there is natural Gas west of Crimea I thought: Why is a Ukrain NATO membership a risk for Russia, there is no change that in Europe NATO

Before realizing that there is natural Gas west of Crimea I thought: Why is a Ukrain NATO membership a risk for Russia, there is no change that in Europe NATO would attack Russia, as European NATO members would not allow it. That is except if Russia expects to be in a war against NATO in the not to long future. (Not necessary start the war though). This behaviour could also fit into this argument, i.e. losing a lot by being trying not to lose the important parts to much. Through it could also be: - Political games including high Generals of the Russian Air Force rejecting getting fully involved in the war. - Putin being paranoid and believing that if they send major Air Force troops to Ukrain then some 3rd party will use this to invade Russia/destroy major parts of Russians Air Force. - Putin hoping to get an excuse to wage war against NATO and therefore is holding back the Air Force to launch a attack against other forces. - Russia being in a much worse economical state then believed, not affording to fly the full Air Force. - Something having subtle damaged huge parts of their Air Force (and is kept secret). Like e.g. there being a problem with some of the materials used to build them, or with their guidance system, or similar. - Russia is falling apart (on a high command level) Putin has lost most power, including command over the Air Force, this is a last desperate attempt to regain power. EDIT: Maybe this post is a bit too much taping into conspiracy theory territory.