'Cheonan'--the proof is in the pudding

The DPRK [Democratic People's Republic of Korea aka North Korea]is right to demand the complete evidence against it in the sinking of the ROK [Republic of Korea aka South Korea] corvette 'Cheonan' in March 2010.
US secretary of state Hillary Clinton, on her swing through northeast Asia, proclaims that the 'proof' of North Korea's dark hand in the sinking is 'overwhelming'. Her voice is but the latest in a chorus of condemnation.
GuarDiary, however, raises the question of how circumstantial is the evidence. And what's more, the matter of the ROK withholding its strong case in a classified and sensitive document.
Why the timidity in the face of the Wagnerian drama which South Korea's president Lee Myung bek has been conducting for weeks now, pointing his baton of blame on Pyongyang?
If there is a 'strong' case to be made before the court of world public opinion, why not argue the case with all its exhibits, in complete transparency?
As long as the ROK is unwilling to put all its cards on the table, doubts will persist, thereby rendering the case of 'he's says, she says', with no one much the less muddled.
If the blame falls squarely on the DPRK's shoulder, make the case without a reasonable doubt!
Pyongyang, the bluster and sabre rattling notwithstanding, is on solid grounds, as GuamDiary observes, in demanding full and indeniable proof, not guilt by past practices in 'terrorism', or analogies with old North Korean weaponry.
As the English expression says: 'the proof is in the pudding'. We are waiting for a serving of the full and complete truth, still.