The Japanese army was able to leapfrog all the strongholds built by Dutch/Allied by using attacking column of no more that 400 miles radius (air coverage). They took Aceh, Plaju, Tarakan, Balikpapan, Cepu, Bojonegoro, Surabaya, Merak, Bogor, Jakarta, Bandung and Cilacap in less than 3 months...