The U.S. Secret Service says it has thwarted a sophisticated threat network, seizing electronic devices scattered across the New York tristate area that had been weaponized to target senior government officials with repeated telecommunications attacks.

An investigation led to the agency’s discovery of SIM servers and cards housed at multiple locations concentrated within 35 miles of the United Nations General Assembly meeting at New York City.

“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 in a statement. “In addition to carrying out anonymous telephonic threats, these devices could be used to conduct a wide range of telecommunications attacks.”

“This includes disabling cell phone towers, enabling denial of service attacks and facilitating anonymous, encrypted communication between potential threat actors and criminal enterprises,” the agency said.

In the largest seizure of its kind, the SIM farms were found hidden in abandoned buildings across the tri-state area and had the capability to fire off 20 million anonymous text messages per minute to crash cellphone towers and block emergency services.

The investigation was conducted by the Secret Service’s Advanced Threat Interdiction Unit, a new section of the agency tasked with “disrupting the most significant and imminent threats.” The unit moved quickly to disrupt the network given the timing and locations of the servers.

“The potential for disruption to our country’s telecommunications posed by this network of devices cannot be overstated,” the Secret Service director, Sean Curran, said. “The U.S. Secret Service’s protective mission is all about prevention, and this investigation makes it clear to potential bad actors that imminent threats to our protectees will be immediately investigated, tracked down and dismantled.”

The Department of Homeland Security’s Homeland Security Investigations, the Department of Justice, the Office of the Director of National Intelligence, the New York Police Department, and other state and local law enforcement partners are assisting with the ongoing investigation.

The announcement of the bust comes as President Trump is due to address the UN General Assembly on Tuesday.