China has responded to Japanese efforts to defend the Senkaku Islands by building a helicopter base on a Chinese island 335 kilometers from the Senkakus, This is within range of transport helicopters that could bring in troops and weapons in under two hours. This is seen as a response to the Japanese decision in late 2014 to purchase 17 American MV-22 transports. This the Japanese did to defend the Senkaku Islands from possible surprise Chinese attack. The V-22s are faster than helicopters but Japanese territory is about a hundred kilometers farther away than Chinese land. So given sufficient warning the Chinese and Japanese occupation forces would arrive on the Senkakus at the same time.
Japan first raised the possibility of buying MV-22 “Osprey” tilt rotor transports in 2013. These would be able to quickly move reinforcements to the Senkakus if the Chinese decided to land troops there and declare such an occupation as proof of Chinese ownership. The Senkakus are uninhabited islets 320 kilometers southeast of the Chinese mainland, 167 kilometers northeast of Taiwan, and 426 kilometers west of Japan's Okinawa Island. Taiwan also claims the Senkakus, which have a total area of 6.3 square kilometers. The islands were discovered by Chinese fishermen in the 16th century and taken over by Japan in 1879. They are valuable now because of the 380 kilometer economic zone nations can claim in their coastal waters. This includes fishing and possible underwater oil and gas fields.
The U.S. has also noted the usefulness of V-22s in the Western Pacific. In 2013 the U.S. moved 23 of its MV-22s to an American base on Okinawa. Both the U.S. and Japan long assumed that the biggest threat was the new Chinese Zubr air cushion craft that could get troops and vehicles to the Senkakus in five hours. From Okinawa MV-22s could reach the Senkakus within an hour. China has been getting more aggressive about its claims on the Senkakus, sending more warships and aircraft near the islands, which Japan considers a provocation and possible prelude to a Chinese attempt to establish small bases on the larger islets. One has 4.3 square kilometers of space and its tallest point is 383 meters above sea level. The next largest has 1.08 square kilometers and reaches 177 meters above sea level. The next smaller islets are .32 and .45 square kilometers and basically the peaks of underwater mountains, as are four even smaller ones, three of which only appear during low tide. The largest island has wild goats and some other small mammals as well as vegetation. The only source of fresh water is rain that collects in depressions and crevices. The five largest islands are frequented by sea birds, sometimes for breeding. For a long time the only human visitors were fishermen with boat trouble or in need of fresh water or some of the unique herbs found on the larger islands. Because of the dispute with China there are now more Japanese tourists.
China has a history of installing small numbers of troops on islets or reefs (via structures built on stilts) whose ownership China disputes. China then supplies these troops at great expense via boat from the mainland and threatens to strike back if its “garrisons” are attacked. Thus the Japanese watch the Senkakus carefully, in case China tries to send in “occupation forces.” The U.S. has made it clear that its MV-22s in Okinawa would be available to move Japanese troops to the Senkakus in the event of an emergency.
The 27 ton MV-22B cruises at 445 kilometers an hour and its endurance is about 3.5 hours per sortie. The MV-22B can carry up to 32 troops or 9 tons of cargo. The Zubr class air cushion vehicles are 555 ton craft that can carry 130 tons (three tanks or a combination of lighter armored or non-armored vehicles). Top speed is 110 kilometers an hour and range is 480 kilometers. The crew of 31 usually stays out less than 8 hours per mission. The Zubrs also carry two stabilized MLRs (multiple tube rocket launchers), 4 short range anti-aircraft missiles systems (Igla-1Ms) and 2 AK-630 six-barrel 30mm close-in weapon systems (CIWS), for defense against anti-ship missiles. Currently China has two Zubrs and two more are on order. The most likely Chinese transport helicopter for this mission is the Russian Mi-8 with a max speed of 260 kilometers an hour.