The Department of Homeland Security and the FBI are urging the nation's law enforcement agencies to remain vigilant for signs of terror attacks in the United States after a series of extremist messages that has popped up on social media sites that they fear could potentially trigger homegrown terrorism.
In a bulletin issued this weekend, the agencies said they are unaware of any "specific, credible threats against the Homeland," and said most threats that have been issued by ISIS supporters are "not credible," but say it is not easy to predict triggers that could lead to acts of homegrown terrorism, reports ABC News.
Lone offenders can be difficult to detect and disrupt, and their plots "frequently involve simple plotting against targets of opportunity," the bulletin said.
Such attacks could occur in retaliation for the United States' airstrikes on ISIS, the report said. ISIS said last week it executed American journalist James Foley in retaliation for the military action, and has threatened to kill another captive journalist, Steven Soltoff.
ISIS has been sending messages
online to recruit members from the Western world, the bulletin noted, and will likely continue its "hashtag" campaigns to reach "potential violent extremists."
The notice points out ISIS has already threatened the nation's major cities online, reports the New York Daily News.
One tweet, posted on Aug. 9 and using the hashtag #AmessagefromISIStoUS," warned: "We are in your state. We are in your cities. We are in your streets," shows photos of an ISIS flag at the White House and at Chicago's Old Republic building, where a handwritten note is shown in the photo, which has a June 20 time stamp.
While such messages may be protected by the constitution if they do not explicitly call for violence, federal agencies are still encouraging state and local law enforcement to be aware of messages that name certain locations or targets, and to report people interested in traveling to conflict zones to fight with terror organizations.
"Many terror organizations refer to Chicago as Obama Town," Ross Rice, a former FBI agent and top security expert told CBS affiliate WBBM
in Chicago. Chicago, which is President Barack Obama's adopted hometown, has become a top target among international terrorists.
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