yushchenko, barely survived a massive dioxin poisoning in 2004. skripal was released from prison as part of a spy swap that included anna chapman, the glamorous russian agent arrested in the u.s. in 2010. british counterterrorism authorities are now leading the skripal investigation, but right now, for all the suspicions of russian involvement, no one really knows what's going on here. david? >> keep us posted. terry moran from london tonight. and next, what could be a major development on the nuclear threat from north korea. it came after a very rare meeting between kim jong-un and south korean officials. afterwards, south korea reporting that the north offered to stop testing weapons if the u.s. agrees to talks. tonight, president trump now reacting, and abc's matt gutman, who was just at the dmz, the highly secured border between the north and south. >> reporter: tonight, for the first time ever, kim jong-un face to face with south korean officials who traveled to pyongyang. afterwards, south korea said the north korean leader appeared willing to suspend all nuclear and missile tests in exchange for talks with the u.s. after first saying the offer may