. >> followed by a conversation with the librarian of congress' carl hayden and the archivist of thenited states, david verio. >> 160 million objects, including 2 million books. >> at 6:30 p.m. eastern, presidential historian edna green medford, douglas brinkley and richard norton smith discuss presidential leadership. >>

. >> followed by a conversation with the librarian of congress' carl hayden and the archivist of the united states, david verio. >> 160 million objects, including 2 million books. >> at 6:30 p.m. eastern, presidential historian edna green medford, douglas brinkley and richard norton smith discuss presidential leadership. >> the greatest american , isident, abraham lincoln bracketed by a the least successful american presidents. >> "washington journal" continues. host: welcome back. joshua hammer is with us. he is a freelance correspondent for "smithsonian magazine." we are talking about his piece in the april 2017 issue titled "a modern odyssey." thank you for joining us. you are joining us from germany via skype. tell us why you wanted to write this story and how you ended up focusing on these two particular refugees. been spending a lot of time in germany over the last couple of years. chancellor merkel opened up the floodgates allowing a million refugees to enter the country in 2015. wholeed to see how that -- how would would unfold given the power level, what's going on in the un

the aircraft carrier "carl vinson" is in the region and vice president mike pence will arrive in seoul on sunday. it's a lot to discuss with the perfect guest. general michael haydens the former head of both the nsa and cia, his memoir "playing to the edge, american intelligence in the age of terror" now available in paperback. general hayden, what's in those cans and how do we know? >> well, michael, we don't know. and i think we're going to have an awful lot of american intelligence analysts looking over parade footage for a very long time to try to determine what may or may not be the status of these missile programs in north korea. frankly, michael, i think the smart estimate is, that there's an inevitability about the north koreans getting to the point we fear and you mentioned, but i don't think they're there yet. i think they're several years away. this is a complex problem but they are solving it one piece at a time, even with their unsuccessful missile tests. so again, inevitability but they're not there yet. >> the moab is a bomb that you're well familiar with given your air force background. talk to me about that weapon. a lot of hype here in the united