One of the greatest mysteries in international security circles is why terrorist organizations such as Al-Qaida do not use shoulder-fired missiles to shoot down passenger planes. The last time there was such an incident was on November 28, 2002, when two Strela (SA-7 ) missiles were unsuccessfully fired at a Boeing 757 Arkia Airlines plane in Mombasa, Kenya.

This is surprising since thousands of shoulder-launched missiles have disappeared from state arsenals, or have been handed over to terrorist organizations, and to this day no one knows where they are and who controls them. After the American invasion of Afghanistan, Russian-made Strelas and British Blowpipe missiles were uncovered in caves used by terrorists.

In the 1980s the Americans supplied advanced Stinger shoulder-launched missiles to the Mujahedeen in Afghanistan to aid their war against the Soviets. A large part of these missiles remained in the hands of the Mujahedeen, many of whom joined Al-Qaeda.

In central Asia, a Strela missile can be bought on the street for just $5,000, and there seems to be no shortage in merchandise. The fall of Gadhafi's army in Libya may allow for more shoulder-launched missiles to reach the hands of terrorist organizations.

The mystery deepens when one realizes that the operation of such missiles is simple and requires no complex training. A Strela-type missile weighs 10 kilograms and can easily be concealed in a car or a golf bag. Its range is five kilometers, so that it can be fired from a house window, far from the take-off and landing strip - a fact that makes preventive measures that much more difficult to undertake.

Most surprising of all is the response of Western states to the threat of shoulder-launched missiles, since it is these countries' planes that constitute prime targets for terrorist organizations. The threat has been met with almost complete disregard.

The West closes its eyes, hoping nothing will happen. Attempts are being made to locate missiles that have disappeared and acquire others through undercover agents, but this is not enough to defuse the threat.

The good news is that in one country at least, the threat is being taken seriously and a system that will provide planes with efficient protection is in advanced development stages.

In July 2009, after a prolonged delay, the Israeli government decided to approve a budget allocation of some NIS 400 million needed to develop an active protection system to be installed in planes operated by Israeli airlines.

The system, called "Sky Shield," is being developed by El-Op, and if things progress on schedule, should be ready for installation on an Israeli plane in about a year and a half.

The system is to be attached to the plane's belly, and can be installed in 30 minutes. It is completely automatic. Four electro-optic detectors will identify the launching missile and shoot a laser to divert it once it is in range.

But while development is progressing quickly, a vehement dispute has flared up, unsurprisingly, between the Finance Ministry and El Al over the question of who will fund the systems' acquisition, maintenance and operation.

The price of each system will be about $1 million, and it will also increase the plane's fuel consumption by about one percent per flight. These are insignificant amounts for the state, but the Finance Ministry has naturally sought to dump the cost on the airlines.

Finally, after many months of wrangling, the security cabinet has decided that the state would cover all the costs. Israel's fleet of passenger planes will soon be the first in the world to be protected from the growing threat of shoulder-launched missiles.