The key pieces in North Korea's secret nuclear jigsaw puzzle are falling into place, revealing the outlines of an increasingly long-range ballistic missile force armed with nuclear warheads.

The picture, although yet to be fully clarified and detailed, is alarming the United States and its Northeast Asian allies, Japan and South Korea, against whom the North is threatening to use its weapons of mass destruction.

The threats raise the hitherto unthinkable specter of nuclear war in Asia — either by design or, more likely, by miscalculation. Such a conflict, in a region that is growing faster than any other major part of the global economy, would produce devastating strategic and economic fallout, almost certainly causing worldwide depression.