The United Nations World Food Program (WFP), which has delivered more than $1 billion in food aid to North Korea since 2000, hopes to deliver another half-billion dollars worth of similar aid this year — but is falling far short of its goal.

So far, the donor nations that provide WFP with all its funds have coughed up only $75.4 million toward a 2009 goal of $503 million — and more than half of that amount — $38.8 million — is food aid that was not delivered in 2008.

The main reason for donor reluctance is the saber-rattling behavior of the North Korean dictatorship of Kim Jong-Il, which culminated on May 25 in a multi-kiloton nuclear explosion, the second North Korean nuclear blast in three years.

Alongside the nuclear tests, which are in violation of United Nations Security Council strictures, North Korea has threatened neighboring South Korea with war, ostentatiously tested medium- and long-range nuclear missiles and is preparing for another such long-range missile test that could take place within days or weeks.

The U.N. Security Council unanimously condemned the recent nuclear blast, and weeks earlier tightened economic sanctions against North Korea in response to its provocative missile tests.

As one result of the reaction, the United Nations' front-line emergency relief agency says it is only able to offer a "partial ration" or fortified foods to 1.8 million North Koreans, leaving 4.4 million of the country's most vulnerable civilians, which WFP had also intended to feed, outside its safety net.

Among other countries that WFP hopes will eventually fill the gap is the U.S., which last June, in the waning months of the Bush Administration, suddenly promised to deliver relief food aid worth about $61.7 million to North Korea, after two years of a tough no-aid policy brought on by the regime's nuclear proliferation policies.

Little more than half of that food aid, in dollar terms, was delivered. The remainder is now in limbo, as a result of North Korea's aggressive pursuit of its nuclear goals, but the money equivalent — about $23.5 million — is still being carried on the WFP books as a 2009 commitment.

The use and potential abuse of U.N. relief and development aid to North Korea has been one of the most sensitive topics at the United Nations in the past few years, as the regime continued to ramp up its nuclear program — and its ties with Iran — at the same time that accounts began to emerge of improper hard currency payments by the United Nations Development Program (UNDP) to the sanctioned regime, improper placement of North Korean government employees in UNDP staff posts, and other violations of U.N. procedures and regulations.

A hefty UNDP-sponsored investigative report, published almost exactly a year ago, found that despite U.N. Security Council sanctions, UNDP's North Korea office, as well as other UNDP offices around the world, continued to hand over millions in hard currency to the Kim regime and to transfer sensitive "dual-use" equipment that could be used in creating weapons of mass destruction.

Click here to see the FOX News story on the report.

UNDP had shut down its North Korea operations, but in January decided to resume them. The latest round of North Korean missile launches and nuclear tests have apparently delayed those plans.

Nonetheless, according to a South Korean government news agency, UNDP is preparing to restart its North Korea program very soon. The agency reported on June 3 that four UNDP members had visited Pyongyang, the North Korean capital, on May 19. It quoted an official with UNICEF, the U.N.'s children's relief agency, who said that two UNDP staffers remained there, "busy with work for restarting their program."

For its part, WFP insists that all of its emergency food operations in North Korea are safe from diversion by the regime. According to a spokesman, they are closely supervised by U.N. staff, under a "strict 'No Access-No Food' policy" — meaning that the U.N. organization only distributes food aid where its non-native staff can monitor the distribution.

Those staffers "monitor our relief food supply chain, by sea or by rail, including transshipment points, and down to provincial and county warehouses, and final distribution points," the spokesman said.

No WFP food in North Korean warehouses is distributed "unless international staff are present to monitor and ensure all food is accounted for," the spokesman underlined.

Those claims are viewed with skepticism by some experts, who consider that WFP monitoring staff are stretched too thin for the effort to be effective.

"There are reports of people getting food then giving it back to the government when the monitors leave the site," says Jae Ku, director of the U.S.-Korea Institute at Johns Hopkins University's School for Advanced International Studies.

Whether those reports are true or not, the current squeeze on WFP's food aid effort means that there is less to inspire any potential diversion. WFP's staffing for the operation has also been reduced, a spokesman said, adding that "requisite levels of monitoring remain in place, and are proportional to the quantity of food being distributed, as per WFP standard practice."

George Russell is executive editor of Fox News.