This is a very bold claim indeed. If the situation was managed effectively, then why did Japan feel the need to resort to bacteriological warfare? Why did it take the gamble of expanding the war to Indochina in 1940? And why, in the face of trade retaliation by the US in 1941, did it take the absolutely desperate decision to go to war against all the Western Allies at the same time?The Chinese hadn't surrendered, of course, but in objective terms the situation was being managed effectively from a security perspective.
And once again you fail to account for the fact that the war in China was bankrupting the Japanese economy.