russia has said it found evidence a bomb caused the crash and isis claimed responsibility. and two people with syrian passports arrested and traces of bomb making chemicals found in a car in the geneva area. the search for more radicalized suspects continues as security is tight. are these latest arrests linked to the paris attacks? i want to bring in cnn's nic roberts robertson. what do we know? >> reporter: they are still looking at the possible links to the paris attacks. prior to the two men being arrested, there was an already heightened terror threat here. some information from u.s. counter terrorism picked up from isis chatter and some associates were here in switzerland. it was during the heightened alert as they searched for the