Judgment, Supreme Court, Bronx County (John E. H. Stackhouse, J.), rendered June 25, 1991, convicting defendant, upon his plea of guilty, of criminal possession of a weapon in the third degree, and sentencing him to a term of five years probation, unanimously affirmed.
*422The arresting officer, who observed defendant for approximately 30 minutes at a deserted subway station, stepping on and off the rear car of three successive subway trains, acted reasonably in approaching him for an explanation of his conduct (CPL 140.50 [1]), and in thereafter conducting a protective frisk when defendant immediately put his left hand inside his left jacket pocket and refused to remove it when requested (CPL 140.50 [3]; People v De Bour, 40 NY2d 210, 223). Concur—Murphy, P. J., Sullivan, Carro and Kupferman, JJ.