North Korea has a flair for the dramatic that often manifests itself in missile tests, the most notable example being the multiple-launch outburst nearly three years ago on July 4 – the day the United States by tradition marks its independence with fireworks displays. Pyongyang’s most recent test lacked the high symbolism of that pyrotechnical extravaganza, but from a strategic standpoint its timing was far more significant: It came as the United States was unveiling a revamped missile defense investment strategy and as Japan was nearing completion of a new space policy that is widely expected to emphasize military applications, including surveillance and missile warning.

Though described as a failure by U.S. military officials, the April 5 launch of a single Taepodong-2 missile served as yet another reminder of North Korea’s determination to develop long-range missile technology. The very next day, by coincidence, U.S. Defense Secretary Robert Gates disclosed plans to increase spending on theater-based missile defense systems while curbing expansion of the current U.S. territorial shield – which is geared toward the North Korean threat. North Korea’s track record – the Taepodong-2 tested in 2006 exploded some 40 seconds after liftoff – would appear to validate the Pentagon’s plans. The Stalinist state has not yet come close to demonstrating a missile capable of hitting the U.S. mainland, much less one capable of doing so with a nuclear warhead. Given that fact, the 44 Ground-based Midcourse Defense interceptors either already installed or planned for Alaska and California are more than adequate; the emphasis in the years immediately ahead should be on testing and improving the reliability of that system.

For Japan, the threat is much closer to home – the missile launched April 5 crossed over Japanese territory, as did a shorter-range Taepodong-1 missile North Korea launched in 1998. The 1998 incident led Japan to break its longstanding taboo on using space for military purposes and initiate the Information Gathering Satellite (IGS) surveillance program. With last year’s passage of the Basic Law for Space Activities – Basic Law for short – the ban on military space activities has been formally lifted, meaning Japan is free to pursue any number of independent capabilities.

Among those that have been under discussion since the Basic Law’s passage are higher-resolution IGS satellites as well as space-based missile warning, communications and signals intelligence systems. According to documents that accompanied the latest draft policy, the final version of which is expected by the end of May, these capabilities could be launched starting around 2016.

Budgetary reality will force Japan to set priorities; missile warning would seem to be the obvious choice given the looming North Korean threat and the fact that Tokyo already has IGS satellites on orbit. Japanese Defense Minister Yasukazu Hamada said as much in an address to the nation’s parliament, or Diet, April 9. Speaking to reporters the following day, Mr. Hamada said an independent missile warning capability would improve the credibility of Japan’s missile defense system, which is being developed jointly with the United States.

But missile warning is not the only choice. Japan will have to think carefully about whether it truly needs an independent capability when it can rely on the United States, a close ally, for that information. One argument in favor of having an independent system is that the information would, at least in theory, be available more quickly – a major consideration given Japan’s physical proximity to North Korea. For many countries, moreover, having an independent capability is important in its own right.

On the other hand, developing a missile warning system will require a big commitment of scarce resources, and the technology can be tricky – as the troubles with the U.S. Air Force’s Space Based Infrared System missile warning program have amply demonstrated. Japan will have to weigh this cost and risk against not only the risk associated with continued reliance on the United States but also the opportunity cost: Opting for an independent missile warning system will surely mean some other capability will be pushed further into the future.