They were brutal for two reasons. First, they saw the Chinese as less than human and the fact let themselves be captured rather than committing seppuku made them even less than that, and yes this includes civilians. Second, they used these terror techniques to break the will of the Chinese to stop any thought of an insurrection. I'm not defending, I'm simply reporting.
"He must be able to mystify his officers and men by false reports and appearances, and thus keep them in total ignorance." -- Sun Tzu, The Art of War
No matter how you look at war it is brutal to both soliers and to civilians. The Japanese were brutal for a reason and it paid off. That is until they attacked the US. Once they did that their time was done. Waking us up and forcing us into WWII was their greatest mistake. If they had waited some and attacked with a bigger force and able to take over Hawaii they may have had a better chance. They would have had to try to strike the main land but with a good base in Hawaii they would have had a better chance and force the US out of Europe to protect the homeland thus allowing the Germans more free reign to take over Europe and then focus solely on Russia.
I don't think the Japanese ever had a chance of invading the US. Hawaii sure, but with 70% of their Army stuck in China and not nearly enough transports they would have been crushed. Had they built a transport fleet you can bet we'd have figured it out and built up a tremendous fleet to dtop them. Add to that that we cut off their oil supply and they had to strike.
That is why they needed to figure something else out before they struck at us. I am sure they could have figured something out once they dealt with China and then be able to commit more forces to the USA.
Maybe, but our industrial output back then was so much larger than any competitor it would have been difficult. We out produced Japan and Germany combined in WW II.
Germany was not going to beat Russia. Russia basically beat Germany in 1942 at Stalingrad and in 1943 at Kursk and their 1943 offensives without an English or US boot in Europe. Had Japan not brought us in it may have taken longer but Germany would have lost and Europe would look different today.
When Japan finally did head our way we'd have had years of indicators letting us know. Our navy would have been much larger than hers and we'd have pulled the Atlantic fleet over. My guess is we'd have found a reason to declare war in 42 and gone in anyway, and without Pearl Harbor slowing us down.
Yeah it was a lot of speculation on when the US would be dragged into the war. But with Japan attacking Pearl Harbor that made it a moot point. I t think that the Japanese people would have done better if the did not attack the US until later. But it is hard to really tell.
Yeah, dealing in hypotheticals is always a dangerous place to be. Could it have made it easier for the Japanese, maybe. But everything would have had to fall in their favor to overcome the might of the US, our population, and our industrial might.