I'm still not sure why Putin as done this. I hear his reasons so far are;
1. He was supporting ethnic Russians in the 2 rebel held areas inside Ukraine.
He already offered everyone in those regions Russian passports, so they could leave. If he did want to take action then Russian forces should have remained inside those regions.
2. His claim NATO was going to allow Ukraine to become a NATO member, against the border of Russia.
There is no evidence that NATO wants a war with Russia, or that they were planning to offer NATO status to Ukraine. The NATO countries along the Russian border as already happened when Estonia and Latvia joined NATO in 2004.
3. Now he's taking over Ukraine because of Nazi's.
I looked in to this last night. I have heard of some of the groups mentioned. But they are a tiny component of the Ukraine army or officials. There as been people with nazi ideologies in many armies in the west, US, UK, Germany etc. It doesn't mean that nazi's are controlling the direction of the country. Also if they are nazi's then how have they ended up with a Jewish leader!?
4. He's stopping Ukraine building nukes so he's taken over those nuclear power plants.
There is no evidence that Ukraine was planning to build nukes. This just seems to be another made up excuse.
Any previous legitimate concerns of the enforcement of the minsk agreement should have been solved diplomatically. The moment he ordered the invasion he lost all credability.