The US Secret Service has said it had dismantled a network of electronic devices that could have crashed New York's telecommunications network in an attack ahead of the UN General Assembly.
The protective agency did not say who was responsible for the sophisticated material but linked it to "nation-state" actors and "individuals that are known to federal law enforcement".
ABC News quoted a law enforcement source briefed on the investigation as saying officials "believe the plot is connected to the Chinese government".
"The potential for disruption to our country's telecommunications posed by this network of devices cannot be overstated," Secret Service Director Sean Curran said.
In a statement released shortly before President Donald Trump began addressing world leaders at the UN headquarters in New York, the Secret Service said the network of devices was uncovered after threats were made against senior US officials.
"In addition to carrying out anonymous telephonic threats, these devices could be used to conduct a wide range of telecommunications attacks," the agency said.
"This includes disabling cell phone towers, enabling denial of services attacks and facilitating anonymous, encrypted communication between potential threat actors and criminal enterprises."
Secret Service special agent Matt McCool said the agency was "working towards identifying those responsible and their intent, including whether their plan was to disrupt the UN General Assembly".
Mr McCool said no arrests have been made so far.
He said the investigation that led to the seizure of the electronics began this spring in an effort to identify what he called the "fraudulent calls" made to senior US officials.
300 servers, 100,000 SIM cards
The Secret Service said the devices it seized were located within a 56 kilometre radius of the UN and included 300 computer servers and 100,000 SIM cards across multiple sites.
"Given the timing, location and potential for significant disruption to New York telecommunications posed by these devices, the agency moved quickly to disrupt this network," it said.
"Early analysis indicates cellular communications between nation-state threat actors and individuals that are known to federal law enforcement," it said.
The New York Times said an initial analysis of data on SIM cards has identified ties to "at least one foreign nation" as well as drug cartel members.
The newspaper said 80 grams of cocaine and illegal firearms had been found at locations where the electronic devices were found.
