(CNN)The leaders of Southeast Asian nations recently took the extraordinary step of warning China that its island-building activities in the contested South China Sea “may undermine peace, security and stability” in the region.

That’s strong language from the usually reticent 10-member Association of Southeast Asian Nations (ASEAN), and shows just how high tempers are flaring over what has been called China’s “great wall of sand” in a strategically important area.

The commander of the U.S. Pacific Fleet, Admiral Harry Harris, has described China’s island enhancement program as part of a “pattern of provocative actions” towards smaller South China Sea states.

But island-building in regions like the Spratly Islands plays well to China’s nationalistic domestic audience and also appears to be aimed at reinforcing China’s territorial and maritime claims in a potentially resource-rich area.

Such activities could, however, have dire consequences for the region’s marine environment and vital fisheries.

Read more: http://edition.cnn.com/2015/05/14/opinions/china-great-wall-sand-spratly/