OP link is a video of a discussion panel about a report which you can download a PDF of here: <a href="https://www.csis.org/analysis/boost-phase-missile-defense" rel="nofollow">https://www.csis.org/analysis/boost-phase-missile-defense</a><p>The TL;DW/TL;DR is that boost-phase missile defense, deemed infeasible years ago, may now be practical thanks to advances in technology (rockets, electronics and sensors, lasers, etc)