I think its based a lot on political ideologies.
In 2013 President Yanukovych, tried to cut ties with the European Union and partner with Russia.
But pro-democratic activists attempted to overthrow the President, who retreated to Russia.
Since then, there has been a huge divide between pro-Democratic and pro-Russian Ukrainians.
Putin is now using his propaganda to say that the Pro-Russian population are being slaughtered…… and they must intervene.