United front against North Korea

Forging a united front against North Korea, U.S. President Barack Obama and South Korean President Lee Myung-bak said the North must abandon its nuclear weapons program and promised a tough approach to Pyongyang.

North Korea, for its part, does not appear to be backing down -- threatening military action -- as recently as Saturday-- if the U.S. and its allies try to further isolate the impoverished country.