Chongming Island juts out of China's east coast midway between Russia and Australia, a choice place to glimpse herons, spoonbills and other migratory birds.

The island district of Shanghai also hosts critical landing points in China for the Internet, which some technology experts say makes it an ideal perch to spy on cyberspace. And binoculars aren't needed around the wetlands to spot traces of a People's Liberation Army unit that, according to current and former U.S. officials, spearheads eavesdropping on North America.

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