The US Secret Service says it has disrupted a network of devices used to carry out assassination threats against US officials and for anonymous communications between threat actors, according to a report from NBC News. In the Tuesday announcement, the agency revealed that it uncovered the network within a 35-mile radius of the United Nations General Assembly, which started this week.

In addition to posing a threat to US officials, the Secret Service said the devices could’ve shut down cellphone towers and emergency communications in the area as well.

The Secret Service began its investigation in the spring following “multiple telecommunications-related imminent threats directed towards senior US government officials.” Over the course of its investigation, the agency found over 300 SIM card servers and 100,000 SIM cards in five locations throughout the New York area. 

“This network had the potential to disable cellphone towers and essentially shut down the cellular network in New York City,” Matt McCool, the head of the Secret Service New York Field Office, said in a video announcing the news. Anthony Ferrante, the global head of cybersecurity practice at the consulting firm FTI, said the system could also have been used for eavesdropping, according to The New York Times.

McCool added that early analysis suggests cellular communications between foreign actors and “individuals that are known to law enforcement.” The agency is currently investigating whether the potential threat actors planned to use the network to disrupt communications during the UN General Assembly. As reported by CBS News, officials said the servers were capable of processing 30 million text messages per minute, adding that the system was “well organized and well funded.”

“These recovered devices no longer pose a threat to the New York tri-state area,” McCool said. “The Secret Service will continue to run down all leads until we fully understand the intent of the operation.”