WASHINGTON—An international operation targeting trafficking in opioids on a clandestine part of the internet called the DarkNet has led to about 150 arrests in the United States and Europe and the seizure of drugs, cash, and guns, U.S. and European authorities said on Tuesday. The crackdown, called Operation Dark HunTor, was announced at a U.S. Justice Department news conference where Deputy U.S Attorney General Lisa Monaco warned cyberspace drug sellers: “There is no dark internet. We can and we will shed a light.” Jean-Philippe Lecouffe, deputy director of the international police agency Europol, hailed the results of Operation Dark HunTor as “spectacular.” He said the operation sends a message that “no one is beyond the reach of law enforcement, even on the dark web.” The DarkNet and dark web are related terms concerning a part of the internet accessible only using a specialized web browser and the assortment of internet …