When tomorrow's historians write about 2003, they will no doubt devote most of their ink to the global campaign against terror and its offspring in Iraq. Yet, with long-range ballistic missiles sprouting up like wildflowers around the globe, those historians may save a few pages to discuss something else about last year: Missile defense went mainstream. 

What was once derided as "Star Wars" has come into its own. Technological advances, determined U.S. leadership, and rampant missile technology proliferation are making missile defense not just a theoretical dream, but an essential piece of the security puzzle for the United States and its closest allies. 

President George W. Bush laid the groundwork for this development in 2001 and 2002. After putting Moscow on notice that he was committed to erecting a missile defense system, he convinced the Russians that it wouldn't upset the U.S.-Russia deterrent balance by offering to slash the U.S. nuclear arsenal by two thirds. With Moscow on board, he then scrapped the anachronistic ABM Treaty, made formal requests for assistance to key allies, and shifted missile defense development into high gear. 

Fittingly, Britain was the first ally to join the missile defense coalition. In February 2003, less than two months alter Washington made its request, the Blair government agreed to software and hardware upgrades of ground-based radar stations at Fylingdales and Menwith Hill. Once used to scan the skies for Soviet bombers, the bases will now be used to peer over the European horizon and into Central Asia, the Middle East, and the Mediterranean borderlands, watching for accidental or rogue missile launches. 

Tokyo had been cooperating quietly with Washington on missile defense research since the late 1990s, when North Korea began to test and deploy medium-and long-range missiles. But it was not until February 2003 that Japan's Defense Agency announced its intention to join the U.S. military for missile defense tests in and around Hawaii. In December 2003 Japanese Prime Minister Junichiro Koizumi gave military officials the go-ahead for construction of a Japanese missile defense system. 

Underscoring the gravity and immediacy of the North Korean threat, Tokyo intends to invest close to $5 billion over the next four years to field the system. Using both land-based missiles, such as modified Patriot PAC-2s and highly sophisticated Patriot PAC-3s, as well as sea-based missiles, Japan's missile shield will help defend its own cities and key U.S. bases. It could be operational by 2007. 

Word of Australia's intention to join the U.S. also came in December, when its foreign minister, Alexander Downer, officially informed parliament of the "strategic decision to put in place a long-term measure to counter potential threats to Australia's security and its interests from ballistic missile proliferation."

As with Britain, the Australian decision has a direct link to the U.S. missile shield, since the U.S. system will depend on monitoring and tracking stations in the deserts of central Australia. The Czech and Danish governments also indicated strong support for missile defense. 

So, in the span of 12 months, a missile defense program that detractors once claimed would alienate Moscow, isolate Washington, and trigger another arms race, has instead blossomed into a multinational coalition that enfolds four continents and enjoys Moscow's acquiescence. As Defense Secretary Donald Rumsfeld has observed, "Leadership in the right direction finds followers and supporters." 

Of course, the international environment itself, teeming with terrorists and tyrants, was also a factor in the mainstreaming of missile defense in 2003. 

North Korea defiantly pressed ahead with its twin terror programs, brandishing missilery and nuclear weapons alike. Last year alone, Pyongyang bragged about having a nuclear bomb, re-opened nuclear facilities with the intent of producing more, and even threatened to test a bomb. Its existing missile technology brings Japan, South Korea, and perhaps even the western United States into range. 

Iran was caught preparing to enrich uranium and testing nuclear-device precursors. According to Undersecretary of State for Arms Control John Bolton, Iran has engaged in "a massive and covert ... effort to acquire sensitive nuclear capabilities." To make matters worse, Tehran conducted a surprise test of its Shahab-3 ballistic missile last spring. With a range of 800 miles, the Shahab-3 can strike U.S. allies in Israel, Jordan, Turkey, Afghanistan, and the Gulf, as well as every inch of Iraq. 

Despite Muammar Qaddafi's stunning pre-emptive surrender at the end of 2003, Libya represents a close call--a cautionary tale of the spread of weapons of mass destruction and advanced missilery. According to U.S. officials and the International Atomic Energy Agency, the Libyan nuclear program was further along than previously thought. According to Jane's Defence Weekly, Qaddafi bought scores of North Korean missiles, had hired teams of North Korean rocket scientists, and was working on a ballistic missile with a range of 590 miles. 

Last but not least, the world saw missile defense in action. Although a June test launch failed to intercept its target, an attempt in December was a complete success as a pair of U.S. Aegis warships off the Hawaiian coast tracked, targeted, and intercepted an inbound missile. Racing toward the target at 8,000 mph, the interceptor missile made contact 85 miles above the earth and proved that we can hit a bullet with a bullet. 

Missile defense also proved its worth in combat. According to the 32nd Army Air and Missile Defense Command, the Iraqi military lobbed nearly two dozen missiles at coalition forces during the war. Most were neutralized by PAC-2s and the previously untested PAC-3s, but one almost struck a key coalition command node in Kuwait. The U.S. military confirmed in May that an Iraqi al-Samoud missile launched on March 27 was on a trajectory to hit the headquarters for ground operations. Were it not for U.S. and Kuwaiti Patriot missile batteries, the enemy missile might have decapitated the U.S. military. In fact, debris from the intercepted missile landed on rooftops at Camp Doha. 

Missile defense won't eradicate all dangers. September 11 disabused us of that quaint notion. Instead, it is one segment in an interlocking chain-link fence of security, which presupposes global engagement and includes genuine alliances, hard-nosed diplomacy, robust inspection regimes, real deterrence, and in some cases preemptive action. 

Pointing to the failed tests and late hits, critics are quick to dismiss missile defense as too expensive and too unreliable. But a 50 percent success rate is far better than the results of doing nothing--a zero percent success rate, a zero percent chance of protecting U.S. troops, a zero percent chance of shielding an entire American city from a missile launch.