The deadly bombings at a Turkish airport could be the start of a new wave of terror attacks, worried U.S officials told NBC News.
"Our long summer of discontent has just begun," a senior intelligence official told NBC News Tuesday evening.
The use of multiple suicide bombers fits the M.O. of ISIS — not the Kurdistan Workers' Party, or PKK — and so does the target, in this case Ataturk International Airport in Istanbul, they said.
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"There are only two groups capable of carrying out such a large scale attack," a senior U.S. counter-terrorism official said. "This does not fit the PKK profile, they go after Turkish targets, not international targets."
“There have been four attacks in Turkey by [terrorists] in the past year,” he told MSNBC.
Officials said they were unaware of any "chatter" preceding the attack. But they said there had been a "heightened state of alert" across Europe for months.
Jeffrey said perimeter security at the airport appears to have prevented the terrorists from penetrating deeper into the airport.
A hero cop who died in the blast may have saved dozens more when he wrestled one of the invaders to the ground.
“A porter who we use, someone we have a long relationship with, was with another customer in the airport and heard an explosion,” NBC News' Richard Engel said on MSNBC TV. “He saw a police officer wrestling a man on the ground, a man he’d tackled. A short time after that, he saw the suicide bomber explode.”