After Istanbul attack, security stepped up at US airports for holiday

With U.S intelligence increasingly confident that the Istanbul airport attack was the work of ISIS, officials are stepping up security at American airports — some concerned about possible plots coinciding with the Fourth of July holiday and the Muslim Ramadan holiday, others seeking to reassure travelers with a visible show of force.

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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.

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The Transportation Security Administration has increased security at major U.S. airports, including JFK and LaGuardia in New York and Atlanta¹s 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.

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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At Los Angeles International Airport, the Fourth of July weekend typically means a more visible security presence. But after the Turkey and Brussels airport attacks, common areas and choke points — such as the terminals and curbside at the departure and arrival areas — remain a concern and a challenge, law enforcement sources told NBC News.

At LAX, the terminals have been targets as far back as 1974, when Muharem Kurbegovic, the so-called Alphabet Bomber, left an explosive at LAX that killed three people and injured 36 others. More recently, in 2002, two people died and four were injured at the El Al ticket counter when gunman Hesham Mohamed Hadayet, 41, walked into the Tom Bradley International Terminal and opened fire before being killed by security.

LAX was also a target of Ahmed Ressam, who told authorities after his arrest in Washington that he planned to detonate explosives at the airport on the eve of the Millennium 2000 celebrations.

Although they are aware of no specific, credible threat at LAX, law enforcement sources told NBC News that authorities were tracking a handful of individuals who could potentially pose a threat in Southern California. That is also happening in many other parts of the nation.