The FBI sent a bulletin Friday afternoon warning law enforcement across the nation to be on the look out for anything suspicious in light of the direct threat made by the terrorist organization the Islamic State.

The joint bulletin, first reported by CBS News, was issued by the Department of Homeland Security in conjunction with the FBI but cites no known threat to the U.S. homeland.

The bulletin asks officers to be “alert and aware of the ISIS threat,” CBS Boston reports .

FBI officials could not be immediately reached for comment.

ARLINGTON, VA – AUGUST 21: U.S. Secretary of Defense Chuck Hagel (L) and Chairman of the Joint Chiefs of Staff General Martin Dempsey speak to the media during a press briefing at the Pentagon, August 21, 2014 in Arlington, Virginia. Secretary Hagel spoke about the terror group ISIS and the situation in Iraq. Mark Wilson/Getty Images 

U.S. law enforcement officials and DHS officials who spoke to TheBlaze say they are extremely concerned that ISIS supporters have already infiltrated the U.S. and that there are sleeper cells inside the country waiting to launch an attack.

“We are living in dangerous times,” said a federal law enforcement officer, who works along the southwest border.

He told TheBlaze that the prior to the rise of ISIS the administration and many senior level law enforcement officials “didn’t really take these threats or the capabilities of these groups as seriously as they should have.”

The threat to attack the homeland in a recent video published by ISIS, which showed the brutal beheading and death of American journalist James Foley, “must be taken seriously,” another U.S. Official said.

ISIS said Foley’s killing was revenge for the recent U.S. air strikes against the militants in Iraq.

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