being take on the protect the city. >> this is where everybody has to be on their toes. i know complacency can set in at times, but not in an event like this. >> reporter: in the wake of the attacks in berlin and nice, 6500 sand trucks and 100 blockers will be stationed around the city, most as a protective barrier around the perimeter of times square to ward off a truck-style attack. >> we live in a changing world now. again, it can't just be about what happens in new york. >> reporter: the nypd is in constant communication with foreign departments, gaining intelligence and sharing police strategy with cities abroad. in london, there's added security at the changing of the guards. heavily armed police were unavoidable in berlin as they stood post behind concrete barriers at a christmas concert. czech holiday markets were heavily patrolled and in france, a boost of 10,000 soldiers on the parisian streets over the holiday period, adding to the officers working around the