(CNN) – Militant group ISIS released another gruesome video, showing the beheading of a second American, journalist Steven Sotloff.
The terrorist group has gained strongholds in eastern Syria and northeastern Iraq, and, according to a former CIA operative, ISIS cells have already infiltrated the U.S.
"The people who collect tactical intelligence on the ground, day-to-day – and this isn't Washington – but people collecting this stuff say they're here, ISIS is here, they're capable of striking," said CNN national security analyst and former CIA operative Bob Baer.
"They don't know what their plans and intentions are. But it's a definite concern," said Baer.