Victor, you’re right to point out how North Korea is moving to another dangerous level in this upcoming “satellite” test next month. Of course, Pyongyang already shot a two-stage Taepodong missile directly over Japan’s main island, Honshu, back in August 1998 (I was in Tokyo at the time). The shock in Japan propelled them to start seriously developing anti-ballistic missile capabilities, both at sea and on land. Today, they’re probably the most capable U.S. ally in missile defense.
Japan has had success in shooting down test missiles in the ascent and mid-course stages of flight, using their sea-based SM-3 missile fired off of Aegis-equipped destroyers (of which the Japan Maritime Self-Defense Force has four ships). And Japan and the U.S. are jointly developing an upgraded version of the SM-3. Tracking is still an issue — if they know it’s coming, then they can be positioned to intercept, but coordinating with the Americans on tracking and fixing an in-flight target obviously improves their chances of success. If Japan does decide to try and shoot down the North’s missile next month, they already know that it will likely fly near Okinawa in the far south, so they can pre-position their ships accordingly. But without American radar or overhead reconnaissance for real-time intelligence, it might be a trickier shot for them. Same goes for the South Koreans, who have three Aegis ships, but less experience in intercepting missiles.
Thus, whether the Obama administration is willing to give all assistance to Tokyo or Seoul in shooting down this missile might turn out to be the crucial element. Right now, I wouldn’t bet on it. However, if Washington refuses to help, it might just be the catalyst for Japan and South Korea to get together to fill in the capabilities they need to do all this by themselves (joint satellites to watch North Korea, remotely-piloted high altitude surveillance drones, sharing targeting information). There’s a long road ahead to get there, but nothing like a potential nuke warhead shooting overhead to overcome decades of mistrust.