Does a brief investigatory stop comply with the Fourth Amendment?

We review de novo the district court's conclusion that a brief investigatory stop comports with the Fourth Amendment. United States v. Hernandez-Alvarado, 891 F.2d 1414, 1416 (9th Cir.1989). "An officer may make an investigatory stop if he is aware of specific, articulable facts which, together with objective and reasonable inferences, form a basis for suspecting that the particular person detained is engaged in criminal activity." Id.; see also United States v. Rodriguez, 976 F.2d 592, 594 (9th Cir.1992), amended, 997 F.2d 1306 (9th Cir.1993). "[T]raffic violations constitute criminal conduct which is sufficient to support a brief investigatory stop." United States v. Baker, 850 F.2d 1365, 1368 (9th Cir.1988).