Is There a Dud Nuke Waiting to Blow in Pakistan?

Pakistan may be sitting on top of live nukes that failed to detonate during recent tests, TIME has learned. "There are strong indications that some devices may not have gone off during Pakistan's tests," reports TIME U.N. correspondent William Dowell. Pakistan claimed to have detonated five devices in its first test, but U.S. agencies detected only one blast. "They allow that it might have been three devices detonating simultaneously, but the seismic strength of the blast was too low to have been five devices," adds TIME reporter Stuart Stogel. Since then, Defense Department sources have told TIME that Pakistan appears to be grappling with how to dismantle unexploded atomic bombs encased in concrete amid a sea of radiation, and which could still reach critical mass at any time. TIME has also learned that U.S. and international are actively investigating the reports.

A spokesman for the Comprehensive Test Ban Treaty organization in Vienna would not comment on whether the agency was aware of reports alleging that some of Pakistan's devices had failed. "We are still awaiting further information and analyzing the data we have already received," Carlos Hernandez of the CTBT told TIME. "Our function is to simply document when and where nuclear test explosions occur, and to measure their size." Pakistan has refused to comment on questions concerning unexploded devices. But you might want to think twice about taking a job as a janitor at Pakistan's Chagai nuclear test site right now.