January 4, 20195 Things to Know About Ground-based Midcourse Defense Got 90 seconds? Learn the basics of what was once called National Missile Defense, and is now called Ground-based Midcourse Defense, or GMD. <span data-mce-type="bookmark" style="display: inline-block; width: 0px; overflow: hidden; line-height: 0;" class="mce_SELRES_start"></span><span data-mce-type="bookmark" style="display: inline-block; width: 0px; overflow: hidden; line-height: 0;" class="mce_SELRES_start"></span>
