So many possible reasons.

Boiler explosion......drifting WW2 mine......Human error in the magazine.

Until they dive on the wreck to see which way the force went (in or out), there's no justification for slanted comment (in either direction).

My take would be that, if the N. Korean Government wanted to rattle sabres or start a fight, there are hundreds of better ways than sinking a corvette.

Wait and see seems to be the sensible option.

Don T.