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After these preliminaries, the Japanese may easily attack the relatively unprotected Netherlands islands of Borneo and Celebes, boring down through the Strait of Macassar to take Tarakan, Balikpapan, Macassar. The Netherlanders have long anticipated such an attack. The Borneo oil ports have been mined and studded with artillery for several months, and oil wells outside both Tarakan and Balikpapan have been prepared for firing. Borneo refineries have been moved to Palembang on Sumatra. For about a year secret airfields have been under construction.
If the attack on Borneo were successful, the Japanese would hope to be well supplied with fuel for the major drive—on Java, then on Sumatra, and finally, from both north and south, on Singapore. Netherlands Sumatra and Java would be the first really tough nuts to crack. The naval and air base at Surabaya is sheltered by Madura Island, and both approaches are mined. The Netherlands East Indies Squadron consists of close to 100 surface craft, and although the waters are so clear that submarines might as well be in fishbowls except at night, there are over 18 modern submarines based on Surabaya. If the Japanese should attempt a landing, the Dutch can muster some 360 planes and a moderately well-trained army of 80,000 (principally for the defense of Java) with G. H. Q. at Bandung.
Singapore is one of the four most formidable naval fortresses in the world (others: Helgoland, Gibraltar, Pearl Harbor). Before the war started, Britain's strength at Singapore consisted of three cruisers, one aircraft carrier, nine destroyers, 15 submarines and a number of smaller craft—only enough to play for time until help came from the British China Squadron (four cruisers), from Australia and New Zealand (eight cruisers, five destroyers, some of which are now in the Mediterranean) and from the Mediterranean (now impossible). Singapore's guns are powerful, and the only successful attack would be a long siege and food blockade. But if the Japanese succeeded in taking the rest of the Indies, they might do something they have long planned on paper and for which they have even formed a company: ignore Singapore's throttlehold on trade with the west by cutting a canal through Thailand's 17-mile-wide Kra Isthmus.