funding for great decisions is provided by pricewaterhousecoopers, llp. (upbeat music) - [narrator] there was a time when the us was a reluctant world power. foreign policy was run by the state department and the us treasury, and largely focused on advancing american commercial interests overseas. - we had american statecraft that largely relied on diplomacy and economic policy. we had secretaries of state that everybody knew their names, we had secretaries of war that nobody had ever heard of. the second world war changed all that. it really brought to the fore a unified department of defense. - policy makers talked in terms of us foreign policy, and defense policy. since world war ii and down to the present moment, policy makers tend to talk in terms of national security policy. national security policy tends to privilege, or to place particular emphasis on the role of the military in advancing us interests. - [narrator] after world war ii, george kennon, a top american diplomat in moscow, sounded the alarm over the existential threat he saw in the sovi