for a potential attack. a strike, some 48 hours ago president trump warned was coming with missiles that are "nice and new and smart." trump later dialed back the urgency, something his u.n. ambassador defended today. >> you don't rush decisions like this. if you rush decisions like this you make a mistake. >> reporter: but haley said there was no mistake about what happened and who was responsible. >> did a chemical weapon attack happen? yes. the u.s. has analyzed, yes, it has happened. >> reporter: after greeting her russian counterpart, haley gave a sharp rebuke over the russian's denial the syrians waged a chemical attack. >> i started to listen to my russian friend and respond, but instead, i'm in awe, vasily, of how you say what you say with a straight face. i really, really am. >> martha raddatz back with us live tonight.