// Four countries, China, South Korea, the United States, and Japan, have dominated the provision of food aid, contributing over 75% of the total since 1995. North Korea has been adept at turning from one donor to another, opportunistically seeking out the least stringent terms.
After peaking at over 900,000 MT in 2001, assistance provided by the WFP fell dramatically over the following years until 2008, when a large U.S. contribution brought up the WFP total. There were two primary reasons for the decline in WFP assistance. The first was “donor fatigue,” as contributing nations objected to the North Korean government’s continued development of its nuclear and missile programs as well as tightened restrictions on donor agencies’ monitoring of shipments to ensure that food is received by the neediest. The emergence of other emergency food situations around the globe also stretched the food aid resources of the United States and other donors. Whatever the causes, the WFP was unable to fill its goal of 150,000 MT for the 2006- 2008 period. During this time, increased bilateral assistance—outside the WFP’s program—that China and South Korea shipped directly to North Korea, as well as improved harvests in North Korea, appear to have made up much of the gap, which generally is estimated to be in the range of 1 million MT per year. //
http://www.fas.org/sgp/crs/row/R40095.pdf
Primarily, China, South Korea and Japan are buying stability in the area. The US is buying influence, particularly on Nuclear weapons. Though those four countries do not appear to be getting what they want for their aid.