So if NK delivered a miniature nuke in 2004, did they already use/test it?
What happened in 2004?
Several smaller explosions could..
The Best Kept Secret of World War Two — Project Seal, the tsunami bomb.
To achieve efficient wave production with sufficient destructive force a number of charges had to be detonated in unison.
The boffins in the Hauraki Gulf determined that a line or array of massive charges totalling as much as two million kilograms, split up into 10 or so equal parts, detonated around 8km from shore, would produce a wave of 10-12m in height.
https:/ /www.nbr.co.nz/article/best-kept-secret-world-war-two-%E2%80%94-project-seal-tsunami-bomb-ck-134614