Q+A: What is behind North Korea's planned rocket launch?

SEOUL (Reuters) - North Korea plans to test a rocket next month that could carry a warhead to Alaska, but which Pyongyang says is the centerpiece of a peaceful program to send satellites into space.

Here are some questions and answers about the launch that North Korea told international agencies would take place between April 4 and 8.

WHY IS THE NORTH CONDUCTING THE LAUNCH?

A successful launch would be portrayed by the North's propaganda machine as a mighty symbol of Kim Jong-il's leadership after a suspected stroke in August raised questions about his grip on power.

It would also be able to show off to all Koreans that it has launched a rocket to carry a satellite just ahead of the wealthy South, which hopes to launch one in July.

Internationally, a launch would signal to U.S. President Barack Obama that North Korea is getting closer to developing a weapon that can reliably hit U.S. territory and should be treated seriously.

On the business front, the secretive state would be able to sell proven missile technology abroad. Weapons sales are one of the few major export items the isolated country has to offer.

IS IT DANGEROUS?

Most experts do not think the launch planned for April poses any immediate threats to the region other than the potential for one of the stages of the rocket to hit something, or someone, when it falls from the sky.

In the long term, any sort of test increases the threat posed by North Korea because it brings it closer to building a missile that can hit U.S. territory. Even a failed test will yield valuable data for the North. Its first and only launch of the Taepodong-2, with an estimated range of 6,700 km (4,160 miles), fizzled out after a few seconds in the air.

Experts said they do not believe the North, which tested a nuclear device in 2006, has the ability to miniaturize an atomic weapon to place on a missile but the secretive state has been trying to develop such a warhead.

Even if it had, they say, North Korea does not appear to have the technology to guide the missile to a target.

WHY DID THE NORTH GIVE THE WORLD NOTICE OF THE LAUNCH?

This strengthens North Korea's case that its motives are peaceful. North Korea contends that every country has the right to peaceful space exploration and that U.N. sanctions barring it from ballistic missile tests do not apply.

WHAT IS THE DIFFERENCE BETWEEN A MISSILE TEST AND A

SATELLITE LAUNCH?

For the United States, South Korea and Japan, there is no difference between the two because North Korea uses the same rocket -- the Taepodong-2. The three countries see any test of this rocket as a violation of U.N. sanctions because the launch is to help the North improve its long-range missile technology.

A complete missile test would include having a warhead re-enter the atmosphere on target, and presents more of a technological challenge than a satellite launch.

Experts are uncertain if the impoverished North can actually produce a working satellite, let alone place it into orbit. But they said North Korea may be able to make a satellite based on the rudimentary designs of early Soviet satellites.

CAN THE U.S. OR JAPAN SHOOT IT DOWN?

The United States or others can destroy the rocket while it is on the pad at the North's east coast missile base called Musudan-ri. The United States also has a vessel in Korean waters that can intercept missiles in flight.

Experts said it takes North Korea about a week to prepare for a launch once it is placed on a pad, making it vulnerable to a strike.

The United States and Japan have anti-missile systems in place along the flight path announced by North Korea but the political risks of shooting down the missile are enormous.

North Korea has warned it would see such a move as an act of war and analysts said a strike on the rocket could easily trigger some sort of conflict on the heavily armed Korean peninsula that has the potential to harm the major economies in the region.

WHAT CAN BE DONE TO HALT THE LAUNCH OR PUNISH THE NORTH?

Not that much.

The United States, South Korea and Japan, are almost certain to call for U.N. sanctions, but they will find their path blocked by China and Russia, both permanent veto-wielding members of the U.N Security Council and unlikely to punish Pyongyang.

In this case, Washington, Seoul and Tokyo will call for tighter implementation of U.N. sanctions imposed after a July 2006 missile test and the October 2006 nuclear test. The sanctions restrict the North's arms trade and financial transactions while banning the import of luxury goods and have not been a strictly applied as some would have liked.

(Editing by Jonathan Thatcher and Dean Yates)