NOOSE
The National Office Of Security Enforcement, or NOOSE, is a law enforcement organization in Liberty City called upon when a wanted level of 3 stars or higher is reached. They'll appear in NOOSE Cruisers, NOOSE Patriots, Annihilators and Enforcers, and well armed. They've replaced the Military and SWAT that was seen in previous GTA games. They are obviously based on the Department of Homeland Security, as well as NYPD ESU and various SWAT teams in the United States.
Trivia
The term NOOSE refers to a type of knot used in public hangings, a method of capital punishment employed around the world in earlier times.