Russia's test of a new long-range missile -- one that a Kremlin official insisted can penetrate any American shield -- ought to wake up anybody who believes missile defense is an issue that went out with the Cold War.

If anything, missile defense is more important now, in an age of terrorism, than it was during our legendary rivalry with the Soviet Union. Although the U.S. is committed to building a missile defense, progress takes time. And, let's not forget, the project was needlessly delayed for years by politicians who falsely asserted that it would spark an arms race.

As the 2008 presidential race heats up, voters ought to use missile defense as one yardstick to gauge how serious the candidates are about protecting the United States from attack. Mere rhetoric isn't enough, though. A better way is to consider if the candidates support the principles behind three key amendments, all related to missile defense, that came up during the recent debate over military spending.

Any presidential candidate who truly favors fielding effective missile defenses for the U.S. should unequivocally support what the following amendments are designed to achieve:

1. Missile-defense funding. Rep. Trent Franks (R-Ariz.) offered an amendment to restore $764 million that the House Armed Services Committee cut from the missile-defense program. The most severe cuts came in the programs meant to intercept ballistic missiles in their "boost phase," shortly after they're launched. The most problematic cut this amendment would have restored was $10 million needed to conduct conceptual studies for a space-based defense against ballistic missiles. Space-based defenses, including missile interceptors, would be the most effective element of an overall missile-defense system.

The Franks amendment lost narrowly, but any presidential candidate who supports restoring these needed funds understands the need for robust missile-defense funding, and space-based defenses in particular.

2. Missile-defense cooperation with our allies. Rep. Duncan Hunter (R-Calif.) offered an amendment to strengthen the U.S.-Israel cooperative missile-defense program. Israel and the U.S. have collaborated on missile defense for quite a while now. Indeed, it has long been U.S. policy to field missile defenses to protect U.S. forces deployed abroad and U.S. friends and allies, as well as U.S. territory.

Such cooperation isn't limited to Israel. We have cooperative programs in place with Australia, Denmark, Germany, Italy, Japan and the United Kingdom, among others. A new arrangement is being negotiated with the Czech Republic and Poland.

The Hunter amendment was passed by an overwhelming majority in the House. Any candidate who tries to facilitate cooperation with our allies on this issue can fairly be described as a genuine supporter of missile defense.

3. Operational status for missile defenses. Finally, Rep. Pete Sessions (R-Texas) offered an amendment clarifying a provision in the defense-funding bill that could have prevented the president from putting still-developing missile-defense systems on operational alert. As the Russian missile test makes clear, the effort to develop and deploy effective defenses lags well behind the threat. It's important, as our missile defenses develop, that the president be able to put elements of the system on-line as they're completed. No genuine supporter of missile defense would deprive a future president of the option of putting the system on alert, a step President Bush took when North Korea launched a salvo of missiles in July 2006.

The Sessions amendment passed, ensuring that future presidents won't find their hands tied when deciding how best to protect the American people.

These three amendments provide important guideposts for judging presidential candidates when it comes to missile defense. True supporters of missile defense will seek to include space-based systems in the overall defense, will seek widespread missile-defense cooperation with the friends and allies of the U.S., and will preserve the option of putting developmental missile-defense systems on operational alert.

When weighing the merits of the candidates on missile defense, don't just take into account what they say. When crucial votes come up, consider what they do.

Baker Spring is the F.M. Kirby fellow in national security policy at The Heritage Foundation (heritage.org).