The conflict between Chechens and Russians reached its peak when the Soviet Union collapsed in 1991, when Chechen nationalists, led by Dzhokhar Dudayev, proclaimed the Chechen Republic of Ichkeria and sought to separate from Russia, causing the brutal First and Second Chechen Wars. In response, Russian military responded brutally against ethnic Chechens, especially in the second war where more than an estimated thousand of Chechen civilians were killed by Russian military.