"This protective intelligence investigation led to the discovery of more than 300 co-located SIM servers and 100,000 SIM cards across multiple sites," the Secret Service said. An investigation into the incident has been launched by the Secret Service's Advanced Threat Interdiction Unit. The Secret Service also said early evidence points to cellular communications between nation-state threat actors and individuals that are known to federal law enforcement. The agency also did not identify the officials who were threatened, the nature of the threat, or the nations that may have been involved. "The potential for disruption to our country's telecommunications posed by this network of devices cannot be overstated," said U.S. Secret Service Director Sean Curran.