We can use this to defeat those evil Russians that are controlling our elections!
>According to the (2001 census), the ethnic makeup of Crimea's population consists of the following self-reported groups: Russians:1.18 million (58.3%), Ukrainians: 492,200 (24.3%), Crimean Tatars: 243,400 (12.0%) [...]
>According to the 2001 census, 77% of Crimean inhabitants named Russian as their native language, 11.4% – Crimean Tatar, and 10.1% – Ukrainian.
>Ukrainian was until 2014 the single official state language countrywide, but in Crimea government business was carried out mainly in Russian.
Source: https://en.wikipedia.org/wiki/Demographics_of_Crimea
Russia on purpose flooded the area with Russians when they last had it, much like China is doing now with Tibet.
You can’t argue this justifies war from another country. If the people vote for (or otherwise self-select) independence and to join another nation that’s very different than a war where the soldiers hide their identity in order to take a region forcefully.