The Department of Justice announced the shutdown of “the largest criminal marketplace on the internet.”

The site, AlphaBay, was launched in 2013 after authorities shut down a similar dark web marketplace known as the “Silk Road.” According to the Justice Department, AlphaBay has been hosting over 200,000 users and at least 40,000 illicit vendors.

While these efforts may only slow the selling of illegal drugs, weapons, and other “dark” material, the announcement shows a continued effort by U.S. and international law enforcement to crack down on criminals.

On July 5, the creator of AlphaBay, Alexandre Cazes, was arrested in Thailand. The United States and Thailand were not alone in the investigation.

As Attorney General Jeff Sessions noted in a speech regarding the incident, “international partners at Europol and in Thailand, the Netherlands, Lithuania, Canada, the United Kingdom, Canada, France, Germany … worked closely with [the United States] to take down the criminal enterprise” that used computer networks across numerous countries.

At the time the site went offline, it contained over 300,000 listings for drugs, toxic chemicals, stolen identification documents, and illegal software.

Shutting down the site was more difficult than one may believe at first glance because of a lack of a central location. The dark web is not accessible through usual browsers like Google Chrome or Internet Explorer, and thus is not easily accessible.

Moreover, the site is only accessible if users operate through a “The Onion Router” (Tor) network, which makes IP addresses difficult to trace.

The site also used only digital or crypto-currencies, which allowed users to maintain anonymity during purchases unless the digital code assigned to each purchase was already known by authorities. Its data can be used across numerous systems.

The shutdown of the Silk Road clearly led to an increase in demand for AlphaBay’s services.

After international law enforcement took control of AlphaBay’s infrastructure, they were able to monitor specific sellers and buyers—and once AlphaBay shut down, authorities were able to watch as buyers and sellers migrated to other dark web marketplaces.

One site, known as Hansa Market, was quick to populate with AlphaBay’s users. Coincidentally, Dutch law enforcement were simultaneously working to shut down Hansa Market.

The case is still under investigation by the FBI, and more such cases are sure to follow.

These efforts highlight the need to combine traditional law enforcement, both domestically and internationally, with law enforcement’s cyber capabilities to crack down on new-age cyber threats.