An offensive elsewhere in China could have no such decisive effect as the stoppage of supplies entering China over the Burma Road. This operation, if successful, might force capitulation of the Chinese. This was clearly shown in the recent operations at Changsha and Ichang. Japan has perhaps 33 divisions in Manchuria and adjacent areas. Continuance of the bulk of these troops on this duty is necessary.
Similar considerations apply to the concentration of the Japanese air forces e .
Estimates of the initial force required for invasion of Yunan, from various sources, British, Chinese, Russian and American, vary from 5 to 10 divisions and all agree on the necessity of using strong air forces. Thus. a major effort would be necessary, including the use of many transports, supply ships, etc. Page 1362 f . If Japan became involved in a long campaign in southwest China, she would be seriously hampered in operations elsewhere. Physical difficulties in the way of a Yunnan invasion are considerable, the most important being the terrain.