Crimea has always belonged to Russia, Krushchev gave it to Ukraine on a whim.
Extreme nationalists were the driving force in the 2014 coup that brought Poroshenko to power in Ukraine.
Recurring pro-Kremlin narrative painting the 2013-14 Euromaidan protests as a far-right uprising which culminated in a coup against the democratically elected President Yanukovych. It fits the wider portrayal of Ukrainian politics as dominated by "fascists."
Radical nationalists played a very limited role throughout the Euromaidan, had not initiated the protests in the first place, and did not install the Poroshenko to power. Petro Poroshenko won the presidency in a competitive and transparent election, as reported by the OSCE. The two most popular nationalist candidates won a combined 1.84% of the national vote, and their respective political parties failed to achieve the minimum electoral threshold in the October 2014 parliamentary race.