The president-elect and the Star Wars president share some common ideas. Both have blanched at the nightmare of America held hostage by the threat of tens or hundreds of thousands of Americans dead from nuclear-tipped ballistic missiles. And both have been morally repulsed by the notion of protecting our nation by threatening to bury an entire enemy population under a forest of mushroom clouds. There has to be a better way.

Ronald Reagan's moral revulsion at the thought of massive retaliation led him to establish the Strategic Defense Initiative -- SDI. He envisioned a global network of missile interceptors that would make missiles obsolete.

Dutch's grand vision survived the derisive objections of naysayers who dismissed SDI as a fanciful variation of Darth Vader's Death Star. And he held firm when the Soviets insisted that he trade away missile defense in return for missile cuts. In the end, however, Star Wars succumbed to post-Cold War Pentagon budget cutters.

But the nuclear threat did not end with the Cold War. Enter North Korea. Its nuclear weapons program put missile defense back on the table. For the last decade, son of Star Wars, a ground-based system capable of killing Kim Jong-Il's missiles, has been under development.

The future of missile defense came up several times in the course of this year's presidential campaign. Barack Obama never rejected missile defense outright. "In a world with nuclear weapons," he declared, "America must continue efforts to defend against the mass destruction of its citizens and our allies." He also promised to "spare no effort to protect Americans from the threats posed by nuclear weapons and ballistic missiles." But, he cautioned, missile defenses had to be "pragmatic and cost-effective." Further, he pledged "not [to] divert resources from other national security priorities until we are positive the technology will protect the American public."

The Obama doctrine made for good presidential politics, giving both missile shield advocates and missile defense skeptics reason to hope he might be in their camp.

But campaigning is not the same as governing. And those who govern must choose.

The new Oval Office "decider" must drop this waffling doctrine soon. For one thing, the latest missile defense test proves, beyond question, that the system works. The December shot provided an end-to-end evaluation of every part of land-based missile defense: from the radars that detect the missile; to the command and control network that sends the orders; to the three-stage interceptor missile that kills the enemy warhead; to the crews in uniform who run all the pieces of the system. Everything worked. Son of Star Wars blew the target missile out of the sky.

Yes, countermeasures designed to test an enemy missile's capability to spoof the interceptor did not deploy. But that just shows how difficult countermeasures are to employ in practice. The bottom line: Today's missile defenses can deal with the state-of-the-art missile threat.

That's good news not just for America, but for our allies as well. The interceptors scheduled to be placed in Europe to defeat a potential Iranian missile attack are a two-stage variant of the California and Alaska-based missiles. There is little doubt that that technology will be adequate to the present danger.

Continued waffling is dangerous. Once he occupies the Oval Office, President Obama should explicitly acknowledge that the system works and declare every intention of extending those defenses to Western Europe. Failure to so will simply invite Russia to try to negotiate the system away, as they tried to do in the Reagan era.

Even to entertain such negotiations would play into Russia's effort to decouple the United States from the new democracies in Eastern Europe. It would also "spit in the eye" of our NATO allies. NATO has officially endorsed the missile defense deployments in Poland and the Czech Republic.

Moreover, official American ambivalence about the ground-based system would encourage Iran and North Korea to move forward with their programs, in the belief that they might one day be able to use their missiles to hold America hostage.

Obama should become a "retro-Reagan" on missile defense. He must lead.

The president-elect should start advocating now to move forward in deploying and funding missile defenses. If he does not, plenty of others around the world are willing to set the agenda for global missile competition ... and the United States probably will not like the results. Obama could spend the rest of his administration distracted from his domestic agenda while he fights fires overseas.

If America does not lead on missile defense, no one will -- and the world, and the reputation of the American president, will suffer for it.

James Jay Carafano is a senior fellow at The Heritage Foundation and the author of GI Ingenuity: Improvisation, Technology and Winning World War II.