North Korea: Why doesn't Japan shoot Pyongyang's missiles down?

North Korea’s increasingly frequent missile tests have prompted calls for the US, Japan or South Korea to use the weaponry at their disposal to shoot the projectiles down.

In July, after a previous test, retired US Air Force general Chuck Wald struck a tough line. “I would try to shoot one of their test missiles down instead of just firing missiles off the South Korean coast out there,” he told the Washington Examiner. “I don’t know what that does. It shows we can fire missiles, I guess.”

Reacting to yesterday’s test, some Japanese social media users expressed dismay at their government’s failure to shoot down the missile that overflew Hokkaido.

A missile shootdown may hold appeal as a third way between a full-scale attack and the continuation of a sanctions regime that is failing to restrain the DPRK's twin nuclear and missile programmes - but such a plan doesn't come without risks as serious as any other in the intractable dispute.

"There is a great deal of hardware already around the peninsula," said Douglas H Paal, former member of Presidents Ronald Reagan and George H W Bush's National Security Council, and now vice president of the Carnegie Endowment for Peace. "I think it is a better than 50 per cent chance we'll see this added to, rather than a further escalation into something kinetic at this point."

Among this hardware is a range of missile defence systems that are all designed to counter just the kind of attack North Korea could mount.

South Korea and the US base on Guam both have THAAD (Terminal High Altitude Area Defense) launchers, with another scheduled to be deployed in South Korea next month, despite Chinese objections.

America, South Korea and Japan all have AEGIS-enabled missile defence ships in the area, and Japan demonstrated its Patriot missile defence capability at an event coincidentally scheduled just hours after the North Korea test.

This arsenal sounds impressive, but experts counsel caution.

"We've been working on this technology for 30 years, and it's still not ironclad," said Mr Paal. "If we shoot and miss, it would hand Kim Jong-Un an incalculable propaganda victory. The only real-world situation where anything like this technology has proved reliable has been Israel's Iron Dome system, which is a completely different situation."

It is also impossible to know if Mr Kim's regime would see the destruction of a missile as a de-escalatory move: it could easily be taken as an act of war.

Even if that risk is discounted, there are additional benefits to not pulling the trigger.

"These tests are for North Korea to experiment with their capabilities," said Mr Paal, "but, less obviously, they help us learn about those capabilities. From telemetry data to the wreckage we can recover, there's a huge amount of information in every launch - not least the clues to their strategy that can be discerned from their decisions.

"The US and the rest of the world have a range of options at present, but it would be unwise to just start blowing missiles out of the sky."