Struggling U.S. airline companies are not in the market for anti-missile systems to protect commercial jetliners from terrorist attacks.

Industry sources and officials said U.S. airlines would be unable to afford the purchase of missile warning and protection systems against shoulder-fired anti-aircraft missiles, deemed a leading threat by Al Qaida.

Instead, the industry will press the U.S. government to increase other security restrictions and provide updated intelligence on threats by "man-portable anti-aircraft defense systems", or MANPADS which were designed for used against military aircraft.

Israel has been a leader in the development of missile warning and protection systems for civilian airliners. The Israeli government plans to equip at least six jets of the national carrier El Al with a derivative of a missile warning and protection system designed for military aircraft, Middle East Newsline reported.

The Rand Corp. has released a report that determined that the equipping of the 6,800 U.S. commercial airliners with missile warning systems were not cost-effective. Rand said the systems that could detect and deflect the missiles were simply too expensive and some of them were unreliable.

Rand said the installation of missile protection and warning systems on the U.S. fleet of commercial airlines would cost $11 billion. Another $2.1 billion a year would be required to operate the systems.

Israel began development of anti-MANPADS on civilian airliners following a failed SA-7 attack on an Israeli passenger jet in Kenya. More than 700,000 shoulder-fired missiles have been produced worldwide and the U.S. military has been plagued by the SA-7 threat in Iraq.

"Resources available for homeland security are limited, so we must strive to get the most benefit from our investments," Rand's homeland security program director Michael Wermuth said. "There may well be other strategy alternatives that could prove to be less expensive and considerably more effective."

Over the next 20 years, the industry would require $40 billion to develop, procure and operate these systems, Rand said in a report released on Jan. 25. The U.S. government currently spends about $4.4 billion a year on all transportation security.

"If we decide as a nation to significantly increase spending on homeland security, then spending this much on anti-missile systems may be appropriate," James Chow, a Rand engineer who headed the project, said. "But given what we spend today, a large investment in technology still unproven in commercial airlines doesn't appear appropriate."

Entitled "Protecting Commercial Aviation Against the Shoulder-Fired Missile Threat," the report examined options for missile warning and protection systems for airliners. Rand said laser systems used on military aircraft to deflect shoulder-fired missile attacks were not sufficiently reliable and were vulnerable to false alarms.

"While developers of the laser systems work to refine and demonstrate the technology, other approaches should be adopted to guard against missile attacks," the report said. "These approaches include expanding efforts to keep missiles out of terrorists' hands, improving security around the perimeter of airports and improving commercial airliners' ability to survive a missile strike."

Rand said laser systems could be circumvented by insurgents. Israel's Elbit Systems and Rafael, Israel Armament Development Authority have been working on a laser-based missile protection system.

"The most-promising near-term solutions to MANPAD attacks are laser jammers, which soon will be commercially available," the report said. "They are designed to disrupt a MANPADS' guidance system, causing a missile to miss its target.