The sheer size of this year’s military budget defies comprehension, with almost half a trillion dollars going to Pentagon programs. But more money does not equal more security — as “missile defense,” the most expensive program of all, demonstrates so well.

In his proposed budget for 2007, President Bush requested another $10.4 billion to continue work on a system that has so far cost U.S. taxpayers more than $130 billion without producing a single workable device.

Missile defense rarely makes front-page news. But as the government throws more and more money at this wasteful and unnecessary program, it deserves scrutiny. Spending on ballistic missile programs has doubled during the Bush presidency. Yet the system remains a high-priced failure. The last three tests of the system’s ground-based element failed. In two, the interceptor missile didn’t even make it out of the launch silo.

Even if it could work, missile defense is irrelevant to the war on terrorism. A terrorist group intent on attacking the United States with a nuclear, chemical or biological weapon would find it cheaper and easier to load the weapon onto a ship, or make it in the United States. It is highly unlikely that terrorists would use a ballistic missile.

The billions lavished on missile defense are better spent on protecting U.S. ports and chemical plants, or locking down loose nuclear materials in former Soviet states and beyond.

So why does this irrelevant and unworkable program continue to receive billions in taxpayer money? Part of the answer lies in pork barrel politics. Boeing, Lockheed Martin, Raytheon and Northrop Grumman, the four largest military contractors, received nearly $15 billion in missile defense contracts between 2001 and 2004. These companies will go to great expense to keep missile defense funds flowing, using timely political contributions to “grease the wheels” for the program’s survival. Two dozen missile defense contractors have given more than $4.1 million to just 30 key members of Congress in the 2001 through 2006 election cycles, according to data compiled by the Center for Responsive Politics.

The top recipients of this contractor largess are members of key committees who are involved in funding missile defense programs or have missile defense facilities in their districts. The largest recipients of missile defense-related donations in the Senate are Alabama Republicans Richard Shelby ($204,334) and Jeff Sessions ($145,250).

In spite of a deficit-ridden federal budget, members of Congress have let missile defense contributions and hearty hometown contracts obscure the true costs of this unnecessary and extremely expensive program. How can we untie the tangled knot of missile defense contractors and Congress? A vigorous public debate about its cost and utility would make an excellent first step.

, This op-ed ran in the Buffalo News on March 24, 2006. William D. Hartung is author of "Tangled Web 2005: A Profile of the Missile Defense and Space Weapons Lobbies" and a senior research fellow at the New School, where Frida Berrigan is a senior research associate. Both are Foreign Policy In Focus scholars.