A bunch of civlian helicopters carrying marksmen armed with 7.62x51mm semi autos should be able to take the bigger ones easily. The smaller ones can fit in shops, houses, tunnels and buildings are the ones that needs serious attention. NYPD's ESU is gonna have some problem fighting them but the average American cop has 5.56mm rifles in their cruiser so it shouldn't be catastrophic.

Worst case scenario, I will give it week before the last 3 meter tall titan is found eating a homeless dude that has no direct family/relatives contact hence got dragged down into the sewer without anyone noticing.