bret: good evening, welcome to washington. i m bret baier. breaking tonight two u.s. adversaries raising eyebrows this national security circles causing real concern here in washington as both country s leaders touted their nuclear ambitions today. russian president vladimir putin saying he will revisit his country s policies on using nuclear weapons while iran is drastically expanding one of its not so secret nuclear sites. we begin with russia. chief national security correspondent jennifer griffin has details tonight lye from the pnc. good evening, jennifer. jennifer: good evening, bret. more nuclear saber ratling from vladimir putin during his second stop in acre shah in search of friends. weapons for his war in ukraine, and a return to the cold war. the veiled threat came thursday during a press conference in vietnam. putin said he was thinking of changing russia s nuclear doctrine, lowering the threshold for the first use of a nuclear weapon. currently russian doctr