WASHINGTON -- US officials are bracing for North Korea to potentially take its "most provocative" military action in a decade ahead of the Nov. 5 presidential election, possibly at the urging of Russian President Vladimir Putin, NBC News reported Friday. Citing six senior US officials, the broadcaster also said that the United States has contingency plans to respond in the event of Pyongyang taking aggressive action in the Demilitarized Zone separating the two Koreas, or shelling South