Kim Jong-un

Small-scale exercises with South Korea have kept U.S. troops ready for conflict with North Korea, defense officials say.

The action followed reports that North Korea had warned of a possible missile launch or nuclear test for late December.

"There is no prospect of denuclearization until North Korea identifies its facilities and the location of its arsenal."

Pyongyang has stopped nuclear testing but officials say there is no evidence that nuclear stockpiles are decreasing.

"Both sides got some of what they wanted, but neither side got everything it was looking for."

One big outcome of the Singapore summit was commitment to accountability for the missing from the Korean War.

The U.S. is also prepared should North Korea resume test missile launches, officials said.

The defection was the first one involving a military officer since 2008 and the 14th involving a soldier since 2000.

Even without a final resolution, it is already clear which winners and losers are emerging.

Promises of North Korea's good behavior in return for concessions from the U.S. have not worked in the past.