THE ISLAND of Formosa, which the Chinese and the Japanese call Taiwan, is a link in a chain of islands stretching from Kamchatka to the Malay Peninsula and sheltering the coastline of the East Asian mainland from the open Pacific. Formosa is parallel to the mainland of China and is separated therefrom by the Formosa Straits, which are 90 miles wide at the narrowest point. It extends from north-northeast to south-southwest with an extreme length of 243 miles, a breadth generally ranging from 60 to 80 miles, and an area of nearly 14,000 square miles -- approximately equal to that of Massachusetts, Rhode Island, and Connecticut combined. Lying between Japan and the Philippines, the most northeasterly point of Formosa is about 350 miles west by south of Okinawa, and its southernmost tip is 225 miles north of Luzon. Due eastward, the nearest land is Iwo Jima, some 1,000 miles distant; and southeastward, 1,500 miles away, lies Guam. In the Straits, about 25 miles from the coast of Formosa, is a cluster of low-lying, storm-swept islets, the Pescadores. These islands historically have been a political appendage of Formosa. With an aggregate area of 25 square miles, they are important only because of their strategic position. The Japanese during their occupation maintained a naval station there.