Russia was the first country in Europe to invade and annex a part of a neighboring country since, what, WW2? If that's restraint, I hesitate to ask what the lack of it would look like.
Turkey didn't annex Northern Cyprus. Nor did Albania annex Kosovo, nor Russia itself annexed South Ossetia, Abkhazia and Transnistria before.
It's the combination of invasion and annexation - effectively, waging war for a formally acknowledged territorial gain - that makes the situation in Crimea unique post WW2.
