REUTERS

ISIS has specifically called for more attacks on the West during Ramadan — which marks its holiest day, the Night of Power, on July 2 and which ends July 5. Officials are concerned that after battlefield setbacks in Syria and Iraq, the terror group is more determined than ever to attack inside the U.S., reads the report.

Read alsoIS behind Istanbul airport attack that killed 36 – Turkish PMThe Transportation Security Administration has increased security at major U.S. airports, including JFK and LaGuardia in New York and Atlanta's Hartsfield-Jackson. That includes the deployment of Visible Intermodal Prevention and Response (VIPR) teams — heavily armed officers, clad in body armor, who sometimes conduct random security sweeps and searches, law enforcement sources told NBC News.

Read alsoPhotos of Ataturk airport attacker published But the TSA doesn't have enough personnel or enough bomb-sniffing dogs to cover every possible attack vector, sources said. In fact, the drop-off and pick-up areas in airports are among the many soft targets in the U.S. — from shopping malls to stadium parking lots — that are nearly impossible to protect from a concerted armed attack, officials said.

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