Upvote:-3
The Japanese excelled at jungle fighting. That's how they were able to sweep through Malaya and take Singapore from the side that the British had left undefended in the idea that it was impossible to move an army there: the jungle.
They also had naval superiority, and were able to wipe out the combined US/British/Dutch fleets in the battle of the Java Sea, leaving the Dutch East Indies effectively undefendable (the island garrisons did what they could but they could never hope to do more than delay defeat long enough to evacuate some people to Australia, which is what the Dutch did).
The island campaign in the central Pacific was basically the same story. With naval superiority (however temporary and sometimes tenuous) over the USA, and the air superiority that brought with it, the Japanese were able to overcome the island defenses that were designed to only have to last a very limited amount of time before reinforcements from Pearl Harbour could arrive.
Once the US Navy recovered from Pearl Harbour and the rebuilding started in earnest, the Japanese window of opportunity closed rapidly, as predicted by admiral Yamamoto by the way, he had advised against dragging the US into the war for exactly that reason, and the US was able to recover lost ground relatively quickly, in pretty much the same way that the Japanese had done but with their far greater strategic reserves allowing them to keep up the pace to the bitter end.
Upvote:5
Neutralized is a strong word, as they weren't out of the war. But with regard to the Japanese campaign conquering SE Asia, they were. All they had left were their carriers and submarines, which they put to good use. But that wasn't enough to stop the Japanese.
The attack on Pearl Harbor and on the Philippines and Malaysia and Thailand and the Dutch East Indies at almost the same time came as a rude shock to the allies and the US.