The vast cyber-attack in Washington began with, of all things, travel reservations.

More than two years ago, troves of personal data were stolen from U.S. travel companies. Hackers subsequently made off with health records at big insurance companies and infiltrated federal computers where they stole personnel records on 21.5 million people — in what apparently is the largest such theft of U.S. government records in history.

Those individual attacks, once believed to be unconnected, now appear to be part of a coordinated campaign by Chinese hackers to collect sensitive details on key people that went on far longer — and burrowed far deeper — than initially thought.

But time and again, U.S. authorities missed clues connecting one incident to the next. Interviews with federal investigators and cybersecurity experts paint a troubling portrait of what many are calling a serious failure of U.S. intelligence agencies to spot the pattern or warn potential victims. Moreover, the problems in Washington add new urgency to calls for vigilance in the private sector.

Read the article “Chinese Hackers Had Long, Coordinated Campaign against U.S. Targets” on bloomberg.com.