safe enjoy 4th homeland security wonderful police officer around u.s. look us.the department homeland security federal bureau investigation issue alert ask local authorities public remain vigilant possible threats follow recent call violence islamic state leaders detail emerge 4th july terror threats new york city nation big police force assign 7,000 officer nearly counterterrorism personnel handle security around independence day events constantly seek creative proactive prepare respond something happen new york police commissioner bill bratton say week name game prevent hundreds thousands people expect flood national mall washington d.c. parade concert fireworks display use 6,500 shell national park service instal 3.4 miles 5.47 km chain link fence 14,000 feet 4,270 meter bike rack almost 350 portable toilets cope crowds.read yahoo video terror threat alert america celebrate july4th watchful eye homeland security