Surely Putin has long understood, better than anyone else, how a few calls and promises from the Kremlin could readily recruit many of these local leaders in eastern Ukraine to win their cooperation in organizing local residents for pro-Russian demonstrations. To an unappreciated provincial councilor who has gotten words of assurance that he or she would be warmly welcomed into Putin's party of power, the idea of secession from Ukraine into Russia could become quite appealing. No bags of cash would be needed.
When he was Russia's President, Boris Yeltsin held the line on the status quo: There would be no territorial adjustments to align the political map with the ethnographic one or to correct historical anomalies. In effect, Yeltsin made what became the borders of an independent, post-Soviet Russia a red line that neither he nor his successors should ever cross. If Putin forcibly separates Crimea from Ukraine and reunifies it with Russia, thus negating Yeltsin's decision and commitment, he will be following the Milosević example -- but with possible consequences that could jeopardize the territorial integrity of Russia itself.