What is the test for reasonable suspicion of criminal activity under the Fourth Amendment?

It is well established that, consistent with the Fourth Amendment, a "government law enforcement agent may subject an individual to an investigative stop upon a reasonable suspicion that the individual is, has been, or is about to be engaged in criminal activity. ... The agent is said to have a reasonable suspicion when he is in possession of specific and articulable facts which, taken together with rational inferences from those facts, reasonably warrant [the] intrusion. " United States v. Villegas , 928 F.2d 512, 516 (2d Cir. 1991) (quoting

[915 F.3d 883]