The FBI's latest arrests in a two-year, international sting operation that has led to the capture of more than two-dozen suspected cybercriminals will likely drive crooks to adopt more sophisticated tactics to avoid detection, security experts say.The FBI announced last week the arrests of three more suspects in Operation Card Shop. A total of 27 suspected cybercriminals have been captured in the sting operation that started two years ago.\u00a0In June 2010, the FBI launched in the criminal underground an online forum called Carder Profit. The marketplace attracted criminals who bought and sold credit card, debit card and bank account numbers; social security numbers and other personal identification information; hacking tools and "drop services." The latter refers to setting up places where goods bought with stolen credit cards can be delivered and then picked up.Should such sting operations have a chilling effect on the use of underground markets, it's likely to be temporary, experts said. "One can reasonably assume that the recent law enforcement activity has been disruptive to illicit online marketplaces at one level, driving them further underground," Stephen Cobb, security evangelist with ESET, said by email.Liam O Murchu, manager of operations for Symantec Security Response, said anonymity and knowing whom you are dealing with has increased in importance among cybercriminals. "Some sellers have stopped selling their wares in public and will only sell to people that have a track record in the underground," O Murchu said.Cybercriminals are also adopting stealthier technologies, said Andrew Plato, president of Anitian Enterprise Security. "Encryption, proxies and obfuscation tactics make it very hard to track these guys down," he said.The FBI operation involved law enforcement in 12 countries. On June 26, the agency announced the arrest of 24 suspects in eight countries, including 11 in the United States.The latest suspects were identified as Nikhil Kolbekar, who allegedly did business on the web as HellsAngel; Eric Bogle, known as Swat Runs Train; and Justin Mills, who goes by xTGxKAKAROT.Kolbekar was arrested Wednesday in Mumbai, India; and Bogle was arrested on July 2 in Red Deer, Alberta, Canada. Mills, who was arrested in Aurora, Colo., on June 27 appeared in New York federal court on Thursday and was released on bail. Federal authorities plan to seek extradition of the other suspects.The FBI-built marketplace mimicked what's known in the criminal underground as a "carding forum." Cards among cybercriminals refer to stolen credit and debit card numbers and carders are people who buy and sell them. The stolen numbers are often used to buy merchandise online or to make fake cards that can be used in the real world.To join the FBI's forum a person had to be recommended by at least two other members or pay a registration fee. The FBI also required a valid email address.Investigators took down the forum in May 2012. During the two years it was in operation, the FBI notified financial institutions and individuals affected by the criminal activity, preventing economic losses of more than $205 million. More than 411,000 stolen credit-card and debit-card numbers were identified, as well as network breaches of a total of 47 companies, government entities and educational institutions.While such stings are bound to make crooks more cautious, the undercover operations are still seen as necessary. "Law enforcement has a tough task, but these stings are a good tactic," Plato said. "Stings might be a little old school, but they work."