Nineteen days after taking power as China’s leader, Xi Jinping convened the generals overseeing the country’s nuclear missiles and issued a blunt demand. China had to be ready for possible confrontation with a formidable adversary, he said, signaling that he wanted a more potent nuclear capability to counter the threat.

Their force, he told the generals, was a "pillar of our status as a great power.” They must, Xi said, advance "strategic plans for responding under the most complicated and difficult conditions to military intervention by a powerful enemy,” according to an official internal summary of his speech in December 2012 to China’s nuclear and conventional missile arm, then called the 2nd Artillery Corps, which was verified by The New York Times.

Publicly, Xi’s remarks on nuclear matters have been sparse and formulaic. But his comments behind closed doors, revealed in the speech, show that anxiety and ambition have driven his transformative buildup of China’s nuclear weapons arsenal in the past decade.