(NewsNation) — Investigators are still piecing together who was involved in a massive threat to New York City's telecommunications network.

The U.S. Secret Service announced it thwarted a plot that, if successfully carried out, would have jammed cell towers and blocked phone service for millions of Americans. It happened just as dozens of world leaders arrived in Manhattan for the 80th U.N. General Assembly.

More than 300 servers and 100,000 SIM cards were seized from five different sites, all within 35 miles of the United Nations.

"This was a case that began as a protective intelligence investigation threat case, and what they uncovered was a major network of telecommunications devices that can be used anonymously and encrypted that can be used to shut down cell towers, not allow acces

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