kyle and valerie brown from south carolina just started their european tour. >> we're more aware of pickpockets than terrorists. terrorists, you just -- what do they look like, what do you do? >> reporter: they say the alert has made them more away of their surroundings. >> there are threats every day everywhere we go and we have to be conscientious of what we're doing. >> reporter: security experts recommend simple steps. >> if i were coming down here today and i was going to the london eye and i was with my family, what sort of advice would you give us? >> this is very, very common sense with what's going on. the security forces and the police around here have it under control. >> reporter: around london today, there were no visible increases in security and few signs that tourists were deterred. this couple from ohio brought their teenage daughter grace here for the first time and have no desire to cut the trip short. >> if we are worried and don't go places because of warnings, then we will miss a lot of wonderful things. >> and they win. >> yeah. >> the terrorists win. >> reporter: there's