The Bush administration said Tuesday it has chosen three companies to develop plans for anti-missile systems to defend U.S. commercial planes against shoulder-fired rockets.

BAE Systems (search), Northrup Grumman (search) and United Airlines (search) will get $2 million each to determine whether existing technology could be used to counter the terrorist threat, said Charles McQueary, the Homeland Security Department's undersecretary for science and technology.

The companies, selected from a pool of 24 that sought the contracts, lead teams that will work on adapting defenses already used on military planes and Air Force One (search). All will test infrared jammers that redirect heat-seeking rockets away from aircraft engines.

Asa Hutchinson (search), Homeland Security's undersecretary for border and transportation security, said the announcement doesn't reflect any specific concerns. The intelligence community has no credible threat information involving shoulder-fired rockets, he said.

The first, six-month phase of the project calls for the companies to develop plans for using the anti-missile technology and to analyze the economic, manufacturing and maintenance issues for placing systems on civilian aircraft.

One or two contractors then will be chosen to conduct more rigorous testing for up to 18 months. After that the Homeland Security Department will recommend to Congress and the administration how to proceed.

Lawmakers who sponsored a bill to equip all domestic airliners with anti-missile devices — estimated to cost $10 billion in all — said two years is too long to wait for the government to decide.

"The threat is simply too severe to allow bureaucrats to set their own timetables to make use of those protections," said Rep. Steve Israel, D-N.Y., who sponsored the House version of a bill by Sen. Barbara Boxer, D-Calif.

Boxer said under the Bush administration's timetable, no planes will have the systems before 2006. "That is not good enough," she said.

Hundreds, and perhaps thousands, of Soviet-style SA-7s — heat-seeking rockets that can hit low-flying aircraft within a range of three miles — are said to be available on the weapons market worldwide.

Concerns about terrorists using lightweight rocket launchers to take down commercial airliners were raised in November 2002 when terrorists fired two SA-7 missiles which narrowly missed an Israeli passenger jet after it took off from Mombasa, Kenya. Officials concluded that Al Qaeda probably was behind the attack, which coincided with a bomb blast at a nearby hotel.

The missiles don't always take down their target. In November, a shoulder-fired missile struck a DHL cargo plane at Baghdad International Airport, forcing it to make an emergency landing at the airport with its wing aflame. All three crew members were unhurt.

The Bush administration has been reluctant to pursue the technology, citing the cost and noting that other security measures adopted since the Sept. 11 attacks have diminished the threat.

Hutchinson said the administration increased security around airport perimeters and worked with other countries to keep the anti-aircraft missiles out of terrorists' hands.

It's estimated that it would cost about $1 million per plane to install anti-missile systems. There are about 6,800 planes in the U.S. commercial fleet.

Airlines say the government should cover the costs for installing the devices.

BAE, which will work with Delta Air Lines and Honeywell International, has worked on anti-missile technology for military aircraft for many years. Spokesman Burt Keirstead said it will focus on ensuring that the civilian versions have low false alarm rates. Reliability is essential to airline efficiency, Keirstead said.

United Airlines will lead a team of 11 defense companies to derive an infrared countermeasure from a system used by aircraft that carry heads of state. The system was developed by AVISYS Inc., one of the 11 contractors.

Northrop Grumman declined to name the airline it is working with to adapt its infrared countermeasure, which protect the Air Force's C-17 cargo plane.

"We already have the technology, we already have proven the system can defeat these missiles, we just need to make it friendly for commercial airline operations," said Jack Pledger, director of infrared countermeasure business development for Northrop Grumman.

Parney Albright, Homeland Security assistant secretary, said that won't be easy. He said the difference between maintaining a military and civilian anti-missile system is akin to the difference in the servicing engines of a race car and family sedan.