John F. Trullo (“appellant”) appeals from a judgment of conviction entered July 18, 1986 in the District of Massachusetts, Walter J. Skinner, District Judge, on a conditional plea of guilty to a one count indictment charging appellant with possession of cocaine with intent to distribute, in violation of 21 U.S.C. § 841(a)(1) (1982). Appellant, having pleaded guilty, reserved his right to appeal the issues relating to his May 2, 1985 stop and arrest.
On appeal, appellant argues, first, that the officers did not have the requisite articulable suspicion, required by Terry v. Ohio, 392 U.S. 1 (1968), to justify the stop of appellant; second, that the officer’s use of a drawn gun at the time of the stop turned that stop into an arrest for which probable cause was lacking; and, third, that the officer’s decision to frisk appellant was unreasonable.
We hold that appellant’s actions and the location at which they took place, when viewed through the prism of an experienced police officer, gave rise to a particularized and reasonable suspicion of criminal activity. We also hold that the officer’s drawing of his gun was reasonable under the circumstances and did not transform the legitimate stop into an arrest. We further hold that the officer was warranted in the belief that his safety was in danger and therefore his pat down of appellant clearly was justified.
While we acknowledge that this is a close case, for the reasons which follow we affirm.
I.
We summarize only those facts believed necessary to an understanding of the issues raised on appeal.
On May 2, 1985 at 1:00 PM two Boston police detectives and a DEA agent in an unmarked car were patrolling that portion of Boston known as the “Combat Zone” for drug activity. The Combat Zone is a high crime area known for prostitution and drug dealing. As the officers were stopped at a light, they noticed a gray Thunderbird automobile stopped on the curb of Washington Street with a man (whom we now know as appellant) at the wheel. Washington Street is the main street of this portion of the Combat Zone. As the officers watched, a second man approached the Thunderbird from the sidewalk and engaged appellant in a twenty second conversation through the open passenger-side window. The second man got into the car and had an additional five or ten second conversation with appellant. The car then pulled out and proceeded for two blocks until it made a right turn onto Hayward Place, a short street which connects Washington Street and Harrison Avenue. The officers followed the Thunderbird in their unmarked car.
While Hayward Place is trafficked during early morning and late afternoon rush *110hours, it was deserted at the time appellant entered it. The officers parked three car lengths behind appellant’s car and had an unobstructed view of it. The officers observed appellant and the second man engaged in a thirty , second discussion with their heads inclined toward each other. The second man then got out of the car and walked back toward Washington Street. One of the officers followed him on foot.
Appellant, with the other two officers following, drove his car out of Hayward Place onto Harrison Avenue where he stopped for a red light. The two officers, who were not in uniform, got out of their car and approached appellant’s car on foot. The officer on the driver’s side of appellant’s car approached with his badge in his left hand and his drawn gun in his right hand. That officer identified himself as a police officer and asked appellant to get out of the car. As appellant opened the door and got out, the officer noticed a “bulge” in appellant’s right-hand pants pocket. The officer asked appellant what it was and patted it with his hand. The officer testified that it felt hard and narrow like a knife. The officer reached into the pocket and found a knife with a spring-activated blade retracted in the handle. The officer then arrested appellant for carrying an illegal weapon in violation of state law. A subsequent search of appellant’s person at the station house during booking disclosed two half-gram packets of cocaine in appellant’s hat. An inventory search of appellant’s car disclosed a fake oil can containing 22 half-gram packets of cocaine.
On May 17, 1985 appellant was indicted on one count of possession of cocaine with intent to distribute in violation of 21 U.S.C. § 841(a)(1) (1982). On June 10, 1985 appellant moved to suppress the cocaine seized from his person and car as products of an illegal search. Appellant claimed that the officers did not have either “articulable suspicion” to justify stopping appellant or probable cause to arrest him. He also claimed that the inventory search of the car was illegal even if the stop and arrest were legal.
In an opinion dated August 5, 1985 the district court granted the motion to suppress in part. The court held that the circumstances leading to the officers’ stop of appellant provided sufficient articulable suspicion to permit a Terry stop. Terry v. Ohio, 392 U.S. 1 (1968). The court held that the officer’s seizure of the knife also was justified under Terry. The court, therefore, refused to suppress the cocaine found on appellant’s person as fruit of a lawful stop and arrest. The court, however, held that the inventory search was in bad faith and impermissible. It suppressed the cocaine found in the trunk. The government appealed that portion of the order suppressing the cocaine found in the trunk. We reversed the district court and held the inventory search to be permissible. 790 F.2d 205 (1st Cir.1986). We did not address the court’s Terry ruling.
On June 16, 1986 appellant entered a conditional plea of guilty, reserving his right to appeal the permissibility of his stop and arrest. See Fed.R.Crim.P. 11(a)(2). On July 18, 1986 the court sentenced appellant to two years in prison. He currently is serving the sentence.
For the reasons stated below, we affirm the judgment of conviction and of course the propriety of the May 2, 1985 stop and arrest.
II.
In Terry v. Ohio, supra, 392 U.S. at 25-27, the Supreme Court recognized that, although the Fourth Amendment regulates police-citizen encounters which fall short of full scale arrests, it does not prohibit encounters based on less than probable cause for arrest. While it is beyond cavil that not all police-citizen encounters implicate Fourth Amendment concerns, there is a grey area into which some encounters fall. The Court in Terry held that more intrusive encounters, short of a full scale arrests, must be justified by reasonable suspicion proportional to the degree of the intrusion. Id. at 19. That suspicion cannot *111be inchoate, but must be based on “specific and articulable facts ... together with rational inferences from those facts____” Id. at 21.
The Supreme Court has enunciated a dual inquiry for evaluating the reasonableness of a “Terry stop”. A court reviewing police action must inquire:
“whether the officer’s action was justified at its inception, and whether it was reasonably related in scope to the circumstances which justified the interference in the first place.”
United States v. Sharpe, 470 U.S. 675 (1985) (quoting Terry, supra, 392 U.S. at 23. See also United States v. Streifel, 781 F.2d 953 (1st Cir.1986) (applying Sharpe standard). In the instant case, having made this inquiry, we answer it in the affirmative and hold that the investigative stop of appellant was reasonable and comported with Terry requirements. In so holding, we believe it is appropriate to state that the facts presented by this case, in our view, represent the outermost reaches of a permissible Terry stop; and it should be borne in mind that “... in law as in life, today’s satisfactory explanation may very well be tomorrow’s lame excuse.” United States v. Vazquez, 605 F.2d 1269, 1280 (2d Cir.1979).
A.
We wish to make clear at the outset that a determination of whether the stop was justified at its inception depends on the totality of the circumstances confronting the officer. “[T]he assessment must be based upon all of the circumstances.” United States v. Cortez, 449 U.S. 411, 418 (1981). As the Second Circuit put it, “We view as wise the admonition of the District of Columbia Circuit that ‘the circumstances before [the officer] are not to be dissected and viewed singly; rather they must be considered as a whole.’ ” United States v. Magda, 547 F.2d 756, 758 (2d Cir.1976), cert. denied, 434 U.S. 878 (1977) (quoting United States v. Hall, 525 F.2d 857, 859 (D.C.Cir.1976)).
The initial factor which the officers considered was the nature of the Combat Zone, the area in which appellant’s conduct took place. “Officers may consider the characteristics of the area in which they encounter a vehicle.” United States v. Brignoni-Ponce, 422 U.S. 873, 884 (1975). See Cortez, supra, 449 U.S. at 411. (“Of critical importance, the officers knew that the area was crossing point for illegal aliens.”) See also United States v. CorralVillavicencio, 753 F.2d 785, 789 (9th Cir.1985) (totality of circumstances includes fact that area known as one in which contraband pick-ups are made); United States v. Rickus, 737 F.2d 360, 365 (3d Cir.1984) (“The reputation of an area for criminal activity is an articulable fact upon which a police officer may legitimately rely.”); United States v. Gomez, 633 F.2d 999, 1005 (2d Cir.1980) (“The car was halted in an area of high narcotics activity — a factor appropriate in considering whether an investigatory stop was proper.”), cert. denied, 450 U.S. 994 (1981); United States v. Constantine, 567 F.2d 266, 267 (4th Cir.1977) (“An area's disposition toward criminal activity is an articulable fact.”), cert. denied, 435 U.S. 926 (1978). Here, appellant’s activities took place in what is unquestionably a high crime area of Boston. The officers testified that narcotics transactions frequently take place there. The district court described the area as “a high crime area. It contains ‘adult’ movie theatres and bookstores and is a center of prostitution and the exchange of various forms of contraband. It has also been the scene of many stabbings and shootings, often fatal.” Location alone, however, is insufficient to justify a Terry stop. Brown v. Texas, 443 U.S. 47, 52 (1979). In Brown the police could articulate no fact other than location, while in the instant case the police pointed to appellant’s conduct which they considered suspicious. It would fly in the face of well-settled precedent were we to *112hold, as appellant invites us to do, that the location was of minimal consequence and should not serve as one appropriate factor in determining the reasonableness of a Terry stop. We decline the invitation.
A second articulable factor upon which we hold the officers justifiably could have relied was appellant’s conduct. The initial conversation between appellant and the individual who approached his vehicle lasted only a few seconds, after which the second man entered appellant’s vehicle. The two drove a very short distance, approximately a block and a half, and turned onto a deserted side street. After parking on that side street the two, with their heads inclined toward each other, engaged in a conversation of short duration. The second man then exited the vehicle and walked back in the direction from which the two had driven. The officers testified that such behavior was indicative of some sort of illegal transaction. In the officers’ judgment a clandestine transaction had taken place, a judgment to which we give appropriate deference.
“The process does not deal with hard certainties, but with probabilities. Long before the law of probabilities was articulated as such, practical people formulated certain common-sense conclusions about human behavior; jurors as fact-finders are permitted to do the same— and so are law enforcement officers. Finally, the evidence thus collected must be seen and weighed not in terms of library analysis by scholars, but as understood by those versed in the field of law enforcement.”
Cortez, supra, 449 U.S. at 418.
The circumstances under which the officers acted “are to be viewed through the eyes of a reasonable and cautious police officer on the scene, guided by his experience and training.” Hall, supra, 525 F.2d at 859. See also United States v. McHugh, 769 F.2d 860, 865 (1st Cir.1985) (“[i]n assessing the import of the evidence, the expertise and experience of the law enforcement officers must also be taken into account.”). The three officers who observed appellant’s actions had collectively some twenty-eight years of experience in law enforcement. The officers also had special expertise in the area of narcotics. Based on this experience and expertise, the officers unanimously determined that they were observing an illegal transaction.
We hold that the actions of the officers, based on the totality of the circumstances, were justified at their inception.
We are not persuaded by appellant’s argument that his actions also could be interpreted as manifestations of wholly innocent conduct. The conversation between appellant and the second man which occurred on Hayward Place lasted only approximately thirty seconds. Thus, it seems unlikely that the two went there to talk or, as appellant suggests, to browse through “an ‘art’ magazine one of them could have just purchased in a Combat Zone bookstore.” Also, since the second man got out of the car and walked back towards the place from which appellant had picked him up, it is unlikely that the second man was seeking transportation from appellant. We could, no doubt, hypothesize some innocent explanation of appellant’s conduct, for “[i]t must be rare indeed that an officer observes behavior consistent only with guilt and incapable of innocent interpretation.” United States v. Viegas, 639 F.2d 42, 45 (1st Cir.), cert. denied, 451 U.S. 970 (1981) (quoting United States v. Price, 599 F.2d 494, 502 (2d Cir.1979)). Accord, United States v. Wallraff, 705 F.2d 980, 988 (8th Cir.1983); United States v. Black, 675 F.2d 129, 137 (7th Cir.1982), cert. denied, 460 U.S. 1068 (1983). It is precisely for that reason that the applicable standard in determining the propriety of a Terry stop is whether a defendant’s acts give rise to an articulable, reasonable suspicion of criminal activity and not whether they can be construed as innocent through speculation.
*113B.
We turn next to the second part of our inquiry: whether the officers’ actions at the time of the Terry stop reasonably were related in scope to the circumstances which provided the justification for the interference in the first place.
Appellant argues that the use of a drawn gun by one of the officers at the time of the initial stop was unreasonable and went beyond the limits permitted by Terry. He contends that such conduct converted the stop into an arrest requiring probable cause. We disagree and hold that the officer’s drawing of his gun was reasonably related in scope to the circumstances which justified stopping appellant in the first place.
It cannot be said that a display of a gun by a police officer automatically converts a stop into an arrest. In so holding here, we follow the approach fashioned by the Second Circuit in United States v. Harley, 682 F.2d 398 (2d Cir.1982). In Harley, the court looked to the nature of the crime under investigation, the degree of suspicion, the location of the stop, the time of day, and the reaction of the suspect as the police approached him to determine whether the officers’ display of weapons was justified. Id. at 402. In the instant case, the officer suspected appellant of dealing in narcotics, a pattern of criminal conduct rife with deadly weapons. The officer’s reasonable suspicions justified the stop. He testified that he had seen many drug transactions take place and the conduct of appellant was consistent with such a transaction. Appellant was stopped in a high crime area. From his experience, the officer knew the area harbored a large number of individuals who carried deadly weapons. While the time of day and the reaction of appellant arguably might be said not to weigh in justification of displaying a gun, the other factors clearly support the officer’s decision.
Further, the officer who approached appellant’s vehicle with his gun drawn testified that he did so out of concern for his own safety. As the district court succinctly stated, “To draw a gun while approaching a suspect in this context is an act of caution____ Given the history of the Combat Zone, this was elementary prudence.” We agree.
C.
Appellant’s final argument is that the officer did not have a sufficient basis to frisk appellant after he stopped him. We hold that this argument is without merit.
“When an officer is justified in believing that the individual whose suspicious behavior he is investigating at close range is armed and presently dangerous to the officer or to others, it would appear to be clearly unreasonable to deny the officer the power to take necessary measures to determine whether the person is in fact carrying a weapon and to neutralize the threat of physical harm____ The officer need not be absolutely certain that the individual is armed; the issue is whether a reasonably prudent man in the circumstances would be warranted in the belief that his safety or that of others was in danger.”
Terry, supra, 392 U.S. at 24-27.
Application of these principles leaves us with no doubt that the officer acted reasonably in frisking appellant and seizing the knife secreted in his pocket.
First, the officers suspected that appellant had just engaged in an illegal transaction, quite probably a narcotics sale. They testified that concealed weapons were part and parcel for the drug trade and that the Combat Zone was notorious for stabbings and shootings. As the Second Circuit has held, “[WJe have recognized that to substantial dealers in narcotics, firearms are as much ‘tools of the trade’ as are most commonly recognized articles of drug paraphernalia.” United States v. Oates, 560 F.2d 45, 62 (2d Cir.1977).
Second, once the officer noticed the bulge in appellant's pocket these generalized suspicions became particularized, permitting the minimal intrusion of a limited *114search of appellant’s outer clothing. Once the “pat down” confirmed that the article in appellant’s pocket had the characteristics of a weapon, the officer was justified in reaching into the pocket and seizing it. The officer had reasonable grounds to believe that appellant was armed and dangerous. It was therefore imperative, for the safety of the officers and the general public, that the officer take the action that he did. We hold that such conduct clearly was reasonable under the Fourth Amendment.
III.
To summarize:
We affirm the judgment of conviction of appellant for possession of cocaine with intent to distribute. We hold that the officers’ action in stopping appellant was justified at its inception and that the nature of the stop was reasonably related in scope to the circumstances surrounding it. We also hold that the limited intrusion in the form of a frisk, which resulted in the seizure of an illegal weapon, was a reasonable search under the Fourth Amendment.
Affirmed.