kim jong-un and stepping onto north korean soil. the first sitting u.s. president ever to do so. that brings us to your weekend presidential brief. a segment where we highlight the most pressing national security issues the president will face when he wakes up tomorrow. with us now, cnn national security analyst sam vinograd. she helped prepare the presidential daily brief for president obama. so president trump did make history by meeting kim at the dmz. walking into north korea. is this a net positive from a security perspective? >> well, ana, it depends if we're playing the long game or short game. president trump cross add line in north korea. i'm not just talking about the military demarcation one. by stepping into north korea, he cemented north korea's status as a normalized nuclear power. from a long-term perspective that has adverse implications for a nonproliferation agenda. other countries may look at kim's example and think there's great benefit in following in his now nuclear footsteps. in the short term the security