BERLIN — Estonia has begun installing the first concrete bunkers along its southeastern border with Russia as part of the Baltic Defense Line, marking a key milestone for the trilateral fortification project despite delays.​​ Five bunkers were awaiting installation as of this week, with Estonian officials targeting 28 bunkers in the ground by year’s end, according to Krismar Rosin, press officer for the Estonian Centre for Defence Investments. The initial batch represents the first phase of a