Not sure about this.
US had been meddling with Russia using Ukraine as base, and the 2014 ousting of the Ukraine Prez at the time was only made worse by the US and EU flaming the issue.
Not saying the war was necessary, but given the large number of times US has been involved in regime changes of various countries (using this Modus Operandi of supporting protesters), taking back control of a region they used to govern (as USSR) is not something absurd to consider.