North Korea now has the capability to conduct nuclear tests without displaying any signs of test preparations to prying eyes. The website 38 North said Pyongyang appears to have altered test preparation practices to make them more difficult to detect, as demonstrated by its latest nuclear test last month.The site said previous images suggest Pyongyang may already have finished digging several underground tunnels at its main nuclear test site in Punggye-ri, which would allow them to conduct another test "with little or no warning."