The leaders (?) of this country know exactly how much China and Russia have contributed to North Korea's armament and nuclear weapons. The lucrative trade that is making them and their accomplices rich is worth losing some American lives if need be.
Yes, the leaders know but aren't saying. As mentioned in the WH press conference yesterday:
North Korea is seeking nuclear help from China after Pakistan has stopped help. So how much does your President think or is U.S. worried about China's and North Korea's military build-up that might one day -- MR. FLEISCHER: Well, if you recall when President Jiang Zemin visited the President in Texas, just two or three months ago, President Jiang said publicly that China opposes any nuclearization on the Korean peninsula. So I think the premise of your question is not quite right. China is working with the United States to make certain that we can resolve the situation with North Korea peacefully and diplomatically. And that is being done in concert with South Korea and Japan and Russia, as well.
China is working against the United States, as well.