April 9 — Following the regime change coup in February 2014 which toppled the elected government of Ukraine — which could not have occurred without the open support of the United States and governments in NATO — Russian leaders repeatedly warned that the entry of Ukraine into NATO was a "red line," which Russia could not allow. The steady eastward expansion of NATO, following the peaceful disbanding of the Warsaw Pact military alliance in 1991, broke pledges given to Soviet leaders that there was no intention to move NATO forces closer to the borders of Russia.