By Nick Childs BBC world affairs correspondent

The UN Security Council will hold emergency talks on Wednesday

The series of missile tests by North Korea has been strongly criticised by the United States and Japan.

The two nations are launching urgent diplomatic discussions, including talks at the United Nations Security Council.

From Washington, the word is that the launches were provocative, but not an immediate threat.

Japan called them extremely regrettable, and said it was considering sanctions.

Australia, whose government is close to Washington on security matters, also condemned the move.

If North Korea intended to attract the world's attention, it succeeded. But to what end?

China's position

These launches may have been a gesture of diplomatic defiance - albeit with a tinge of embarrassment over a key rocket failure.

There will be discussions in the UN Security Council - but probably not much in the way of immediate action as the key parties gauge each other's reactions.

These latest developments sharpen the debate over the best way of reviving the stalled six-party talks

These missile firings put China - perhaps the closest thing North Korea has to an ally - in a difficult position.

Washington is likely to argue it is time to be tough with North Korea.

But will China and South Korea interpret the missile firings as evidence that Pyongyang is not susceptible to pressure?

And what does that do to the chances of a united response?

Also, what pressures, like sanctions, could usefully be applied anyway?

The missile question must be seen in the context of broader concerns about North Korea's nuclear weapons developments, what they mean for stability in the region, and more general worries about weapons proliferation - although a significant test failure may raise new questions about just how advanced Pyongyang's weapons programmes really are.

These latest developments certainly sharpen the debate over the best way of reviving the stalled six-party nuclear talks with the North.

They will hardly make the Bush administration more willing to compromise.

But they have also reignited complaints from domestic critics of the administration that it has failed to engage diplomatically with North Korea for years.