But since Mr. Kim gave a speech in Berlin in March, pledging a huge commitment of resources from the relatively rich South to help rebuild the impoverished North, relations between the two countries began their dramatic shift.

Some in the administration say the impoverished North is looking for a face-saving deal in which it might return to respecting international restraints, in return for economic benefits.

Those from the impoverished Communist North who accomplish the risky leap over can be rewarded with freedom and relative prosperity in South Korea, which offers arrivals from the North nearly $30,000 in resettlement aid.

Washington appeared to be on the verge of resuming sending food aid to the impoverished North, and there were high hopes Pyongyang was prepared to halt its nuclear programmes and allow the return of international nuclear inspectors.

Trans-Korean gas lines and railroads are planned, projects that could provide revenue to the impoverished North.

In particular, they may lead to the establishment of an efficient capital market and banking system, essential if the two Koreas reunified and the South had to rebuild the impoverished North.

And a South Korean official said today that his country fully expected to pay the impoverished North for these reunions.

The main target of the message, delivered by state television KRT and attributed to the North's National Defence Commission, was South Korea's conservative government headed by President Lee Myung-bak who has pursued a hardline stance against the isolated and impoverished North.

Mr. Lee repeatedly alluded to recent revelations that North Korea had been secretly developing nuclear weapons and said that if he won on Dec. 19, he would make a clean break with recent policies that sought to obtain the cooperation of the impoverished North by providing economic aid.

After a decade of warming ties, relations plummeted in 2008 after Mr Lee took office with a firm policy of linking aid to the impoverished North to its commitment to dismantle its nuclear programme.