It is undisputed that at least some people in Crimea and Donbas wanted to secede, it appears in Donbas the vast majority wanted at least more independence and voted for it (with 96% for it, which has been confirmed by western pollsters which were trying to find irregularities but found 95% of voting intention pointing towards just that), whereas in Crimea it may have been as low as 30% according to some claims of western interests.
Even a single person does of course have every right to secede with his property - every single person, not just a town or a region. And the right to contract anyone he wants to his defense. Thus, however much russian forces are doing wrong, it most certainly is not an offensive war or an invasion, it is quite clearly a defensive war given they were welcome by at least some people in Crimea and Donbas.
However regrettable it may be that they intend to still be statists.
None of this implies of course that russia is clean or didnt do bad things in the process. But they did not invade Crimea or donbas, they were invited.