via The Telegraph Despite North Korea's highly-publicized missile tests, relatively little is known about the actual size and capabilities of its arsenal.

The regime is understood to have substantial numbers of short- and intermediate-range missiles such as the Nodong, a variant on the Scud missile.

With a range of around 1,000km, the Nodong could in theory strike in South Korea and Japan. However, its poor accuracy makes it an ineffective battlefield weapon and it is unlikely North Korea would be able to pinpoint U.S. military bases in the region, although it could cause serious civilian casualties.

The middle-range Musudan missile is of major concern to Japan as its 4,000km capability would allow the North Korean regime to strike anywhere in Japanese territory. Estimates of the size of North Korea's Musudan arsenal vary widely, with figures ranging from only a dozen to more than 200.

The Taepodong 1 was North Korea's first multi-stage missile, a significant technological development where the weapon depends on different thrusters at different times. However it has proved a poor performer, with limited range and unreliable accuracy.

However, its older brother, the Taepodong 2, is treated far more seriously by U.S. defense authorities. The 40m missile is believed to have a range of 6,000km, meaning it could in theory hit Alaska. In December 2012, a variant of the Taepodong 2 successfully launched a satellite into space.

Barry Pavel, a former senior director for defense policy at the White House's National Security Council, described the launch as "a milestone."

"It's the same general technology as is required for intercontinental nuclear missile, so it's a concern," he said