counterterrorism. and 83 sanitation trucks filled with 16 tons of sand blocking cross streets to thwart an attack like the one in nice, france. nypd's chief of counterterrorism -- >> given the current climate around the world and sense of uncertainty in some countries, the propaganda that's out there, we wanted to make certain. >> reporter: what specifically can a sand truck do that a patrol car can't do? >> you're not going to move a sand truck. >> reporter: on monday, a new york city taxi driver was accused of supporting isis. earlier this month an isis propaganda magazine called on supporters to target the parade itself but concerns this holiday season are not limited to the u.s. the state department issued an alert monday to u.s. tourists traveling in europe warning that terror groups continue to plan attacks. >> the main point that we were trying to convey to potential travelers is to be vigilant. >> reporter: in france, seven men were arrested for planning