Does a Border Patrol agent have reasonable suspicion to justify stopping a truck?

We review de novo the district court's determination that Border Patrol Agent Cole had reasonable suspicion to justify the investigatory stop of the appellant's truck. 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.