On November 12, North Korean scientists took Stanford professor Siegfried Hecker and two colleagues to the Yongbyon nuclear complex. The North Koreans led the Americans to a building that Hecker, former head of the Los Alamos nuclear laboratories, had visited in February 2008. The structure had been transformed into a “stunning” uranium enrichment facility, Hecker would later write.

That revelation brings to an end the long-running debate inside the U.S. intelligence community over whether the Democratic People’s Republic of Korea has an active uranium enrichment program. North Korea acknowledged that it had such an effort back in 2002. But the North Koreans later claimed their admission was a misunderstanding. And in the years since, the intelligence community has had little knowledge of the North Korean nuclear program—it is, after all, the most secretive project of the world’s most secretive regime. There was no fresh intelligence to cast doubt on the program’s continued existence, because there was little new information about the program at all.