Ter-Petrosyan led Armenia alongside Defense Minister Vazgen Sargsyan through the Nagorno-Karabakh War with neighboring Azerbaijan. The initial post-Soviet years were marred by economic difficulties, which had their roots early in the Karabakh conflict when the Azerbaijani Popular Front managed to pressure the Azerbaijan SSR to instigate a railway and air blockade against Armenia. This move effectively crippled Armenia's economy as 85% of its cargo and goods arrived through rail traffic. In 1993, Turkey joined the blockade against Armenia in support of Azerbaijan.