Desultory speculation continued Monday as the world waited with more or less bated breath to see whether North Korea is going to conduct another nuclear test.
One Defense Ministry official claimed Seoul is discussing a possible military response with Washington. He did not go into detail but said "everything" is on the table.
Military experts were reduced to extrapolating information from the little they know about the North's previous nuclear tests in 2006 and 2009.
In 2009, the ministry says the North dug a tunnel that ended in a spiral or pigtail-shape at the Punggye-ri nuclear test site, and built nine blast doors and three walls aimed at absorbing the shock and preventing leakage of radioactive materials.
This apparently made it more difficult for the outside world to come to any definite conclusions about the success or failure of the test. Experts now worry that a similar arrangement will once again leave them in the dark about whether North is using uranium or plutonium in the fresh test, because that depends on measuring escaped radioactive materials.
The ministry also disclosed a diagram of the inside of the Punggye-ri nuclear test tunnel based on screen images aired by the North's own official KCNA news agency in September 2010.
The ministry says it was able to reach some conclusions by discussing the picture with a research team led by a U.S. nuclear expert who has been to North Korea, Siegfried Hecker.