China does not approve of North Korea carrying out nuclear tests, but unlike in the past when the North's economic ally has warned of heightening international tensions, this time China says its worried about damage to its own environment. That's not to say China will be taking drastic action against its neighbor, Reuters' Benjamin Kang Lim reported exclusively on Wednesday, but the Middle Kingdom is reportedly putting quiet pressure on North Korea to call off its third nuclear test, preparations for which it has said are "almost complete."

China's official line on North Korea's nuclear testing plan so far was that it "might jeopardize peace and stability on the Korean peninsula and in Northeast Asia," according to a UPI report of Chinese Vice Foreign Minister Cui Tiankai's comments to the press. Even though China doesn't exactly have a stellar environmental record itself, the Chinese public has long been worried that North Korean nuclear testing "would pose a huge environmental threat to China's northeastern provinces," according to research by the U.S.-based Arms Control Association. Now, those environmental concerns are driving China's opposition to North Korea's tests as much or more than global security worries, reports Reuters' Lim, based on unnamed sources "with ties to Pyongyang":

China feared a radiation leak and damage to the environment from a blast, the source added.

"China also complained about the environmental damage to the area after the first two tests."

When North Korea conducted nuclear tests in 2006 and 2009, it caused environmental damage to the mountain straddling the border with China. North Korea ceded part of the mountain to China in 1963.

Since a North Korean rocket failed last month, Pyongyang's been at a loss to show off its military prowess, and its been touting this nuclear test as a way to do that. But as Lim points out, "China is the closest thing to an ally North Korea has," so it may not want to go around nuking their shared border.