It's from Xinhua, so it might just be translation. Or it might be style, "oil" is used in the sentence right before it. Or it might be intentional slant. Xinhua doesn't tend to be environmentalist in slant.
True enough — you can't tell the original author's slant from a translation. Otherwise: “tar” = opponent; “oil” = neutral to supporter.
BTW, it would suit China's interest just fine; if the U.S. refused to take any more oil from the oil-sands. That would spur on the building of the pipeline across the Rockies to a new west-coast tanker port — whence the oil would be shipped to China.