vietnam war, the political turmoil with lyndon johnson announcing he will not seek another term in large part because of vietnam and the heightened tensions with the cold war and the soviet expansion into czechoslovakia. >> bad year. it was a year where it seemed like all of these strands seemed to come together at once. north korea became more, you know, opportunistic, trying to actually launch a kind of situation where they might be able to open up a southern front, taking advantage of the vietnam war and the ted offensive and czechoslovakia, which was this moment where like so much of 1968 where it seemed like everything might change for the better and then the cold war comes in and slams it all down. >> explain what happened with the soviet moving into czechoslovakia and why that was such a significant milestone in 1968? >> well, in a way,