President Ronald Reagan's "Strategic Defense Initiative," or "Star Wars," has cost the United States $60 billion since the mid-1980s. Congress most recently financed SDI in 1999, when, quietly and with bipartisan support, $6.6 billion was doled out for further development of national missile defense. Yet it hasn't always been clear where the money goes, what has been developed so far or whether any of these systems will ever work.

According to Powell, national missile defense, like the Internet, is essential to America's future. Rumsfeld, who was secretary of defense from 1975 to 1977 under President Ford, explained in his testimony that defense shields "work without being fired" because "they alter behavior." Both men also have declared the Anti-Ballistic Missile Treaty of 1972 to be virtually obsolete.

Frances FitzGerald, historian and Pulitzer Prize-winning author of "Fire in the Lake," offered an in-depth account of SDI under the Reagan administration with her acclaimed work "Way Out There in the Blue." Heralded for its clear and elegant style, FitzGerald's book unveils the daunting complexities surrounding missile defense, from its bizarre scientific origins to Reagan's thorny personal motivations to its role in the arms race.

Salon spoke with FitzGerald about what lies ahead for missile defense.

Now that the Republicans are in office, missile defense is a hot issue. But it seems as if "Star Wars" and all its progeny are still shrouded in mystery.

No one ever knew quite what it was. It was a bunch of research programs. Reagan promised it would protect us, like a roof over our heads. It always had to do with weapons in space.

How did it change with the Bush and Clinton administrations?

There have been many "sons of Star Wars." They're mostly just ideas too. The first Bush administration supported "Brilliant Pebbles," the notion that these things rattling around in space would intercept missiles.

Clinton, though, was developing a ground-based system. They built various sorts of prototypes. Missile defense isn't one thing -- it's radars and all kinds of stuff. It's not a scientific problem -- having it all work at once is the problem. And Clinton's system has various problems; two out of three tests have failed. A big issue is whether or not the system can deal with decoys.

What was the Clinton administration's rationale for it?

Rationales change all the time. The Clinton administration rationale was to protect us from "rogue states" -- which did not mean Russia or China. It meant Iraq, Iran and Korea. Then, they decided that they weren't "rogue states" and Madeleine Albright started talking about "states of concern."

But all of those countries have unique considerations.

The problem with China is that, essentially, it has ICBMs [Intercontinental Ballistic Missiles], but it only has 20 of them. We kept trying to reassure them that our system wasn't aimed at them. But if it actually worked, it might suppress their deterrent force. Therefore, if you build anything bigger, it might definitely affect them. So what choice do they have but to build up more ICBMs of their own?

With Russia it's another problem. They have something like 6,000 strategic warheads. They want to bring strategic warheads below 2,000, but they're not so keen on doing that if we're building up our defense.

Maya Angelou reads from "The Heart of a Woman"