Nuclear Security Summit

North Korea and friction in the South China Sea complicate Obama's 'rebalance' toward Asia

Late in his first term, President Obama announced a new emphasis on Asia and the Pacific Rim, a way of pivoting from the morass in the Middle East and focusing on a peaceful, booming region that the first Pacific-born president saw as the future.

He has visited Asia regularly since then — and will return at least twice this year for economic and security summits.

But with notable exceptions, much of the administration's self-proclaimed "rebalance" has been dominated by emergency security matters, including North Korea's defiant nuclear tests, friction with China in the South China Sea, and the growing threat of cyber-espionage and digital theft.

On Thursday,...