On the dark-web drug market Empire this week, business proceeds as usual. "Satisfied customer, will be back," writes one user on the product page of a meth dealer with the handle shardyshardface. "Excellent," reads a plaudit posted by a buyer of the opiate oxycodone. "Bravo," says another for a $5 sample of fentanyl, one of 18 reviews posted on the product's profile page in the last week. In all, Empire lists over 18,000 narcotic offerings, including hundreds for oxycodone alone.

Judging by that buzzing trade, there's little hint that just the week before, global law enforcement announced the takedowns of two of the world's largest dark-web drug sites, known as Wall Street Market and Valhalla. Or that the most popular market, called Dream, had taken itself offline at the end of last month, perhaps sensing law enforcement closing in. Or that a multiagency US law enforcement task force devoted to stemming opioid sales on the dark web arrested more than 60 people in a major operation the month before.

On Wednesday, the FBI and Europol announced their latest win: The takedown of dark-web news and information site DeepDotWeb, which had quietly made millions of dollars from offering promotional links to black market sites in a kind of underground affiliate marketing scheme. "We think it's going to have a huge impact," FBI special agent Maggie Blanton, who leads the bureau's Hi-Tech Organized Crime Unit, told WIRED. "We viewed DeepDotWeb as a gateway to the dark web."

A dark web market calling itself Nightmare has 28,000 narcotics listings and remains online after law enforcement's recent crackdown.

Taken together, those operations represent the most far-reaching collection of law enforcement actions against the dark web's economy in at least two years. "You’re seeing the evolution of a coordinated law enforcement effort," the director of Europol's European Cybercrime Centre said. "It’s not whack-a-mole anymore."

But despite those wins, a years-long war of attrition seems to be exactly the pattern that the dark web's booms and busts now follow, argues Carnegie Mellon computer scientist Nicolas Christin, a longtime dark web researcher. In an economy where the demand—drug-addicted users—remains constant or growing, that's only to be expected.

"History has taught us that this ecosystem is very, very resilient," Christin says. "It's part of a cycle, and we’re in the chaotic part of the cycle. We’ll have to see how it recovers. But if I were a betting person I would put more money on it recovering than on it dramatically changing."

Lather, Raid, Repeat

The cycle Christin describes—law enforcement takedowns followed by a slow but robust recovery—has played out on the dark web again and again, repeating roughly every year or two. After the late 2013 takedown of the Silk Road, the first real dark-web drug market, more than a dozen replacements rose up to fill the demand for anonymous online narcotics sales. A massive crackdown called Operation Onymous followed in late 2014, seizing a broad swath of the dark web and arresting 17 people by exploiting a vulnerability in the anonymity software Tor, which serves as the dark web's fundamental cloaking tool.