The U.S. and Britain have been buying Russian portable (shoulder fired) anti-aircraft missiles. This is part of a program to help protect military, and civilian, aircraft from terrorists using such missiles. It is believed that the results of these tests are shared with other countries (perhaps even Russia, which has not tried to interfere with these purchases, and has lost aircraft to its own missiles.) At the same time, U.S. government efforts to get airlines to equip their aircraft with anti-missile equipment are running into obstacles. The problem is that there have been so few missile attacks on commercial aircraft (none in the U.S. or Britain, and very few anywhere else). So the airlines are reluctant to equip their fleets with the expensive (several million dollars per aircraft) systems. The airlines know that these anti-missile systems will add to the maintenance burden (the systems have been used by military aircraft for years, and have a maintenance track record). Another complex item that can fail, and delay a flight. The cost will add a few dollars to each passengers ticket, and will take aircraft out of service to have the systems installed. There’s also the potential for lawsuits from damage done when you get a false alert. The systems are so expensive because they use lasers to blind any missile (rather than flares, used in older systems, and even more of a problem when there is a false alarm.) The airlines believe that such systems might, in the end, cause more of a threat than they protect everyone from.