The fact is that between February and March 2014, unmarked Russian soldiers occupied and blockaded the Simferopol International Airport, most of Ukraine's Crimean military bases, and the Supreme Council of Crimea. The Kremlin stated that no Russian troops were active in the region, but many little green men were operating in this region while disguised as pro-Russian separatists.

After two months of denial, on 17 April 2014, Russian president Vladimir Putin confirmed that the Russian military had been operating in Ukraine.

So by Putin's own account here, sending troops into Ukraine they of course started the war. All of which is conveniently left out of this article. Some great reporting here....