Victor Cha, Korea chair at the Center for Strategic and International Studies, made the prediction after analyzing data on North Korean provocations related to South Korean elections.
North and South Korea are technically still at war because their 1950-53 conflict ended in a truce, not a peace treaty.
South Korean and USA officials and 38 North have been saying for weeks that North Korea could test a bomb at any time and speculation was rife that it could coincide with celebrations last Saturday to mark the 105th birthday of North Korea's founding father, Kim Il Sung.
The long-scheduled tests in the Pacific are part of the US military's overall ballistic missile defense program to defend against North Korean or Iranian threats - but are, for now at least, aimed at ensuring the US can defend against a threat from North Korea, US defense officials said.
Ryan said he was encouraged by the results of efforts to work with China to reduce tensions, but that it was unacceptable North Korea might be able to strike allies with nuclear weapons. Top military and civilian Pentagon officials are "thinking through every course of action".
She said that she wanted Pyongyang to see that the U.S. was not an aggressor. North Korea routinely labels such exercises preparations for invasion.
The North has warned of a nuclear strike against the United States if provoked. The latest draft statement dropped "through dialogue" and Russian Federation requested it be included again.
North Korea's Vice Minister of Foreign Affairs, Han Song Ryol, told CBS News in Pyongyang that the situation between the us and North Korea was the worst it had ever been, and that his country was ready to fight a war if provoked.
The official blamed the mixup on a lack of follow-up with commanders overseeing the movements of the USS Carl Vinson aircraft carrier.
Mohd Anwar also said earlier that the government's negotiations with other countries such as the Philippines, Myanmar, Arab countries and in the Asia Pacific region prior to this, had gone well, too.
China's influential Global Times newspaper, which is published by the People's Daily, the Communist Party's official paper, wondered whether the confusion was deliberate. "China and the United States and South Korea, Japan, we all share that same interest".
"In the case of our super-mighty preemptive strike being launched, it will completely and immediately wipe out not only United States imperialists' invasion forces in South Korea and its surrounding areas but the U.S. mainland and reduce them to ashes", it said.