American Intelligence Fails Again

WASHINGTON — North Korea showed a visiting American nuclear scientist earlier this month a vast new facility it secretly and rapidly built to enrich uranium, confronting the Obama administration with the prospect that the country is preparing to expand its nuclear arsenal or build a far more powerful type of atomic bomb.

Whether the calculated revelation is a negotiating ploy by North Korea or a signal that it plans to accelerate its weapons program even as it goes through a perilous leadership change, it creates a new challenge for President Obama at a moment when his program for gradual, global nuclear disarmament appears imperiled at home and abroad. The administration hurriedly began to brief allies and lawmakers on Friday and Saturday — and braced for an international debate over the repercussions.