Database: imdb
Question: List all the directors of movies about nuclear weapons
SQL: select t3.name from director as t3 join directed_by as t2 on t3.did  =  t2.did join movie as t4 on t4.mid  =  t2.msid join tags as t5 on t5.msid  =  t4.mid join keyword as t1 on t5.kid  =  t1.id where t1.keyword  =  "nuclear weapons";