The FBI has beefed up its surveillance of Syrians living in the United States ahead of a possible US military attack on Syria, The New York Times reported Sunday.
The domestic intelligence agency and the Department of Homeland Security have also alerted federal agencies and private firms that any US strike could trigger cyberattacks, according to the report.
Hackers who claim to support Syrian President Bashar al-Assad, and collectively known as the Syrian Electronic Army, have made several disruptions in recent months on American companies, including the Times.
The newspaper said FBI agents are set to interview hundreds of Syrians in the coming days.
US officials are especially concerned because Syria's close ally Iran has warned that any military action on Syria would leave Israel in flames.
The FBI and Department of Homeland Security have issued a classified bulletin alerting federal, state and local law enforcement officials of potential threats caused by the Syrian conflict, the Times said.
It said senior FBI officials have also directed the bureau's field offices to follow up with sources linked to Syrians as part of an effort to identify any talk of a retaliatory strike. And Syrians currently under investigation will be placed under closer scrutiny.
"They're not starting from scratch - the field offices know what they have in terms of sources and investigations, but this is a directive for them to redouble their efforts and check their traps," a senior US official told the Times.