That absolutely can be a WWII bomb. They are still finding unexploded artillery shells from the first world war in France!
Let me repeat that, hundred-year-old shells are still underground, intact, and the explosives in them are just as powerful as when they were manufactured.
Chemicals in fuse can slowly combine until they detonate.
The odds of someone planting more explosives in a field potentially containing a dozen WWII bombs from multiple attacks are remote.
You are not addressing anything of my question. I don't care if 99.9999999% of bombs that go off are from WW2. Not every bomb that goes off is from WW2. How did they determine if this bomb was actually from WW2? Is it just an assumption or did they check something? The article did not clarify that point and just stated it as a fact.
I understand that is what is usually used, but I was asking for the actual details which was scanty in the article. Is this what they did or are they still looking into the forensics?
Because it's a silly question. The airport was bombed in WWII by the US, just like the rest of the country, and Japan wasn't in any war since then, nor was it in any war before then when it would have had such bombs dropped on this location (there was a naval war with Russia in the 1900s, but that didn't result in bombs dropped on Japan).
So basically you're asking for forensic evidence to prove that this bomb wasn't the result of time-travelers or teleporters or something equally fantastical. It's a ridiculous question. Of course it's an unexploded WWII bomb, what the hell else would it be?
Let me repeat that, hundred-year-old shells are still underground, intact, and the explosives in them are just as powerful as when they were manufactured.
Chemicals in fuse can slowly combine until they detonate.
The odds of someone planting more explosives in a field potentially containing a dozen WWII bombs from multiple attacks are remote.