Not sure how reliable it is. But if this is true:
“For some the resignation of Japan’s Interior minister might be related to it.”
Then it would indeed be a very serious situation. A government would do this for a few reasons that I can think of:
1. They got wind that something in the country they've invested in is about to go seriously wrong (destroyed economy). If it were what we've been fearing, Japan wouldn't go through this PR risk. They'd sell them off gradually or exchange them for commodities gradually.
2. They need to gold or other commodities because they are planning an attack or counter on NK and they suspect China will come to NK’s aid against Japan, which sets the stage (potentially) for WWIII, with Russia helping China.
3. Their economy is about to implode for some reason and they want something more stable than US dollars.
4. They were purchasing something they didn't want anyone to know about. They claim to be non-nuke, but I doubt that they are (that is, I suspect they are nuke-equipped). If they are not, however, they could have been trying to buy some key components to get up to speed fast (again, fearing NK and China and wanting some way to defend themselves).
Just thoughts and ONLY MHO.
Or, could it not be impending doom-based, but simply that the Japanese suspect great enough coming devaluation of the US dollar and US bond values that they want to sell, sell, sell—but not to so anger their greatest military protector and economic market?
Japan has stockpiled enough enriched uranium to make approx 1000 Nukes