their nuclear ambition. that's a big ask. to get that, we will have to have some verifiable and over a period of time with inspections. i'm not sure we get that immediately. i think the conversation is much better than having no conversation. >> ifhe north koreans do what the u.s. wants, secretary pompepompeo is promising unique security assurances for the north koreans. what concessions would you be comfortable with in terms of american military power in the region, for example, reducing the u.s. troop level, removing nuclear capable submarines and bombers from the korean peninsula? >> i think everything should be on the table, including removing our troops. i would say that that would have to do with verifiable, denuclearization. really, since it takes time to do some of these things and it takes time to believe that your adversary will do them, i think it should be a gradual lessening of tension, of sanctions,