Oh how times have changed when it is the South Korean President asking the US President to do something to pressure North Korea:

President Lee Myung-bak communicated with U.S. President Barack Obama by phone to ask the U.S. to apply pressure on instead of dialogue with North Korea after conveying South Korea’s decision to become a full participant in PSI. Spokesman Lee Dong-kwan reported that Lee said we needed to remember that North Korea had received compensation, including a reopening of dialogue with the U.S., from the international community when it conducted its first nuclear test in October 2006. The spokesman added the president’s conclusion, therefore, is that the international community needs to work closely together to respond so that the patterns of events are not repeated. The White House said President Obama expressed thanks for South Korea‘s announcement of its full-scale participation in the PSI.  [Hankyoreh]

If you are wondering there are ways to pressure North Korea if someone finally gets the will to do so.