I was stunned to hear the General saying "China, up to 50 years ago... The war-making tendency was almost non-existent, as they still followed the tenets of the Confucian ideal of pacifist culture." It is obvious MacArthur had only a very shallow understanding of the Chinese history or the Japanese history for that matter. Granted that it is not a military leader's job to analyze the deep historical background of a conflict, but did he actually think the Chinese as the helpless victims of the aggressive Japanese, as explained in an educational pamphlet for the military, GI Roundtable: What Shall Be Done about Japan after Victory?
Apparently, MacArthur was in for a big surprise when he faced the atrocious Chinese and Koreans in the Korean war, and concluded "Through these past 50 years the Chinese people have thus become militarized...has become aggressively imperialistic, with a lust for expansion and increased power normal to this type of imperialism." It is amazing that MacArthur did know nothing about Mongol Empire or the last dynasty, Qing Empire (lasted until 1912) that came out of Manchuria, took over China and ruled Mongol, East Turkistan and Tibet as well, following the Mongol Empire and many empires came before them. The Chinese culture has been developed within these empires. The Confucian ideal has been just that, an ideal that no one bothered to follow in China. In other words, the Chinese did not become militarized nor aggressively imperialistic overnight in 50 years.
The Qing dynasty quit fighting the Western colonial powers after the Opium War, not because they were following the tenets of the Confucian ideal of pacifist culture, but because they realized it is easier and safer to let them have part of China. After all, China wasn't theirs to begin with. China was only a colony to the Qing dynasty who was ruling the vast Qing colonial empire.
Japan, on the other hand has never been a colonial empire all through the 2000 years of its known history, until it took over the Pacific islands from the Germans after the WWI. Actually, Japan avoided to make them colonies by structuring it as trusteeship. Taiwan and Korea were not colonies. They became part of Japan, just like Alaska and Texas became part of the U.S. Manchuria was an independent country reestablished by the Qing dynasty under Japanese protection, just like Japan has been an independent country under the U.S. protection since 1952.
Chinese imperialism and savagery is rooted in their glorious 6000 years of history, history of being rule by the hoarding nomads. For the rulers of China, the rest of Asia has been actual or potential vassal states, Japan included. That is one of the reasons China chose to side with the Western colonial empires. They chose to fight against Japan rather than fighting the Western colonial empires that have been taking over the coastal areas of China, because it was upsetting for them that Japan, a vassal state in the Chinese mind, was dominating the Chinese. By fighting against Japan alongside the Western colonial empires, China had the opportunity to make Japan or other parts of Asia its vassal state or colony as one of the victors, just like Japan did after the first World War. Actually, that is what China started to do soon after the U.S.-Japan war ended.
After 7 years in Japan and 2 years of the Korean war, however, MacArthur did not take the view expressed in the pamphlet that Japan was the aggressor nation greedily seeking to expand her territory. In stead, he sided with the Japanese claim that Japan was provoked into a war of self-defense. In his testimony on May 3, 1951 before the Armed Services and Foreign Relations Committees of the United States Senate, he stated "There is practically nothing indigenous to Japan except the silkworm. They lack cotton, they lack wool, they lack petroleum products, they lack tin, they lack rubber, they lack a great many other things, all of which was in the Asiatic basin. They feared that if those supplies were cut off, there would be 10 to 12 million people unoccupied in Japan. Their purpose, therefore, in going to war was largely dictated by security."