overseas tonight, and the british government is now putting russia on notice. prime minister theresa may leaving little doubt that she believes russia is most likely to blame for the chemical attack against a former russian spy and his daughter. and there is news tonight on the chemical agent that was used. abc s chief foreign correspondent terry moran on this again tonight. reporter: chilling scenes in the quiet english city of salisbury. troops donning chemical warfare gear, securing sites contaminated by the nerve agent used to try to kill former russian spy sergei skripal and his daughter, yulia. and today, prime minister theresa may told parliament the weapon was russian made. it is now clear that mr. skripal and his daughter were poisoned with a military-grade nerve agent of a type developed by russia. it is highly likely that russia was responsible. reporter: called a novichok agent, a next generation chemical weapon up to ten times deadlier than vx or sarin. it attacks th