[Petrosius]

Ukraine sent their tanks to Donetsk and Luhansk, in violation of the peace agreement they signed with Russia. That's why Russia intervened.

Donetsk and Luhansk are Ukrainian sovereign territories; it is not Russian territory. Fighting broke out because the Russian puppets refused to implement the Minsk agreement by conducting a vote that would have lead to autonomy within a united Ukraine. But more to the point, there would not have been any need for the Minsk agreements if Russian had not earlier invaded these Ukrainian provinces.

[Right_Wing_Madman]

Fighting broke out because the Russian puppets refused to implement the Minsk agreement by conducting a vote that would have lead to autonomy within a united Ukraine.

Actually, you have it backwards. Ukraine was supposed to allow self-governing elections in Donetsk and Luhansk by the end of 2015, but Ukraine never sanctioned these elections. And when Ukraine's parliament passed a bill in 2018 officialy disavowing self-governance for the two regions, Minsk 2 couldn't be salvaged and the Russians started preparations for a second war against Ukraine.