First, in 2014 Russia was already in Crimea, with military bases, per agreement with Ukraine. Second, in the Donbas the population is heavily ethnic Russian (compare this to the Sudeten Germans in 1938), and would welcome returning to Mother Russia. Third, Ukrainians west of the Dnieper want to remain independent. What Putin is actually encouraging is a hot Ukrainian civil war.
The “hot” civil war is over since 2015, with the de-facto independence of the rebel areas.
Both Russia and Ukraine do not want to escalate it.
The Russian objective is to return Donbas and Lugansk to Ukraine on terms fixed in Minsk agreements and be done with it.
Nothing indicates the opposite, except Western agitation, encouraging Ukraine to forcefully return the breakaway republics and label the hostilities the “Russian aggression”.
Assumptions that Ukraine is ready to go on the offensive in the Donbass,
.... the Secretary of the National Security and Defense Council called “fiction”.