 Final plans for the ships were never completed, and the ships were never constructed.The Japanese invasion of Manchuria in 1931 marked a period of increasing belligerence from the Japanese Empire, and as the decade progressed the Dutch grew concerned about the security of their East Indies colonies.The islands, which included Java, Sumatra, Borneo and part of New Guinea, were enormously important both politically and strategically to the Dutch, who had lived and traded there for more than three centuries.