An alarming newly rendered map by China’s mapping authority reportedly includes 80% of the South China Sea–a major passageway for international trade–as within China’s sovereign borders.

As Forbes writer Gordon G. Chang notes, “each year, more than half of the world’s annual merchant tonnage passes through the South China Sea as well as a third of the global trade in crude oil and over half of LNG trade.”

The new map, which has yet to be released, has diplomats worried, reports the New York Times. Chinese official Wu Shicun denies that the newly drawn map seeks to expand China’s borders. 

“Beijing’s assertion of sovereignty over that body of water does not necessarily mean it will close the South China Sea off to international commerce,” says Chang. “Yet that would be the next step.”

Historically, the South China Sea has been designated as international waters.

News of the newly drawn Chinese map comes as a the Obama Administration has extended an unprecedented invitation for China’s navy to participate in the 2014 Rim of the Pacific (RIMPAC) naval exercises near Hawaii.

President Barack Obama will meet with Chinese President Xi Jinping this week in California.