The US has found that when it comes to North Korea, best try working through a country that really knows the communist state.
That's why President Obama today urged China to do more to restrain North Korea.
Obama met with his Chinese counterpart, Hu Jintao, on the sidelines of a security summit in the South Korean capital, Seoul.
Obama said earlier that China's efforts to influence its Communist ally had been ineffective.
North Korea is preparing to launch a satellite next month, which the US and its allies believe is cover for a long range ballistic missile test.
"It's not the satellite itself that's a concern in the West," says Miles Pomper, an expert with the Monterey Institute's Center for Non-proliferation Studies. "It think it was John F. Kennedy who once said that the only difference between rockets and missiles is attitude."