Deter Rens Doesnt Work News Today

>> reporter: film maker lucy walker has interviewed more than 100 nuclear arms experts and nuclear weapons are the greatest threat in the world because of proliferation to rogue nations, accidents and terrorist groups. >> deter rens doesnt work. terrorists dont have, you know, any way of being deterred. >> reporter: harvard and ucla professor has a ph.d. in nuclear engineering and consults regularly with the u.s. government on national security. he has seen walkers film. >> its certainly true th...