 Because of the secretive nature of North Korea and small yield of the test, there remains some question as to whether it was a successful test of an unusually small device (which would have required sophisticated technology), or a partially failed "fizzle" or dud.A scientific paper later estimated the yield as 0.48 kilotons.It was reported that the government of the People's Republic of China was given a 20-minute advance warning that the test was about to occur.