For decades, Taiwan's army was waiting for Chinese marines to pour across the white beaches of Dongsha atoll, but now fishermen from China are a much bigger concern.
The Chinese fishing vessels are often armed with dynamite and cyanide as they approach the atoll, now a marine national park, and its distance of more than 400 kilometres (250 miles) from Taiwan makes it hard to defend.
"The biggest problem is that Taiwan is so far away, and China is so close," said Chang Chong-tsou, director of Dongsha Marine National Park, as he stood under a cloudless sky viewing the vast expanse of the South China Sea.
"Lots of boats come here from the mainland to fish. There are too many of them, and we don't have the capabilities to chase them all away."
Dongsha atoll, which from the air looks like a near-perfect sandy white circle against a deep blue sea, became Taiwan's first marine national park in early 2007.
The move came after years of concern about the ecosystems at Dongsha, which contains less than two square kilometres (0.8 square miles) of land but boasts a rich marine life with an estimated 600 species of fish and more than 100 species of corals.
However, excessive fishing and natural causes such as the El Nino weather phenomenon have contributed to rapid degradation.
One reef site had 45 species of coral in 1994, but four years later, the number had been reduced to just three.
The status as a marine park may have signalled Taiwan's determination to protect Dongsha's coral environment, but the Chinese fishermen, some based little more than 200 kilometres away, remain a concern.
"We're up against fishermen from Vietnam, the Philippines and Hong Kong," said an official stationed on the island.
"But we're really close to places in south China like Guangdong and Hainan provinces, so the number of Chinese vessels is a great deal bigger."
Taiwan can trace its control of Dongsha back to the end of World War II, when China's Nationalist government took over the islands from the surrendering Japanese.
When the Nationalists were forced by the Communists to leave for Taiwan in 1949, they took their control of Dongsha with them.
The communist government, now on better terms with Taipei than at any other time in 60 years, has never seriously challenged Taiwan's control of Dongsha, perhaps reasoning it would get it all back through reunification anyway.
With the Cold War over, Taiwan's marine corps has relinquished the job of managing Dongsha, handing over the responsibilities to a handful of Coast Guard members.
It is a suitable change of guard in a post-Cold War world, where military attack is no longer the sole or even the primary threat faced by a society.
"Environmental protection is an important part of our job aside from protecting territorial sovereignty," said Sung Tzu-yang, a Coast Guard official.
The general public is not allowed on Dongsha, but this could change, and as early as five years from now tourists may be allowed to visit, albeit in limited numbers to protect the environment.
At the moment, however, the biggest concern is not to make money on the atoll, but simply to help it survive the onslaught of Chinese fishermen.
"When we chase them in the east, they emerge in the west. If we chase them in the north, they turn up in the south," said Chang, the national park director.
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