That part is not a scam.
However, their only contact for obtaining SAMs was a Russian undercover cop. They had no other sources. (this has been covered both on ABC, CBS evening news, and Nightline). They most likely never actually traded in SAMs before (given their lack of sources). This FBI and Russian police admit this. They had no criminal records.
This part of the story:
...a dangerous arms dealer and his accomplices who were willing to bring missiles into the United States to shoot down passenger jetliners.
The way that it is written, it leads you to believe that these guys had plans of their own to shoot down passenger jets. That is not the case, and they are not being charged with that. It was undercover FBI officers who were posing as 'terrorists' who told them they had plans to shoot down passenger jetliners.
This ruse was further enhanced for about 36 hours of the news cycle when it was added that the Russian undercover cop suggested to Lakhani the arms dealer that a particular missile would be suitable for shooting down Air Force One. This part of the story (the 'assassination plot') faded away fairly quickly since yesterday.
There were no terrorists involved here, no intelligence gathered on al Queda, the police freely admit that none of them are suspected of being connected to al Queda, and were most likely motivated by money. One could argue, that since there were no actual terrorist contacts, and no actual SAM missile (the Russians shipped a fake), the entirety of the government's case against these guys boils down to a thought crime: ie., their INTENT to smuggle a missile, if they had ever been able to locate one without the police's help. Kind of like when someone gets busted for selling fake cocaine. It's still illegal, even though it's not actually cocaine.
THAT is why I call it a scam. Given that they had no sources for obtaining these SAMs without police help, this arrest didn't prevent terrorism anymore than a sweep of crooked pawn brokers would.
And THAT is why I'm a bit surprised that they are squeezing so many 'terror, terror, terror' stories out of this sting.