truck-style attack. >> we live in a changing world now. 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 is added security at the changing of the guards. heavily armed police were unavoidable in berlin as they stood posts behind concrete barriers at a christmas concert. czech holiday markets were heavily patrolled and 10,000 officers on the peresian streets working around the clock. >> translator: we're giving of ourselves and our time and at a cost to ourselves and our families. >> reporter: nearly 2 million people expected in times square. the extra police presence a noticeable addition to keep new york city safe. >> if you're coming down to times square, rest assured it will be a safe venue. >> wus within the last few weeks we know members of the nypd have