As described here, kudzu was a Japanese vine imported to the US to control erosion. Instead, it became the plant that threatened to overwhelm the South.

Just as introducing non-native species into a region can have unintended consequences, we have to be careful about what happens if a genetically modified species gets released in the wild. This could happen through malice, as may have been the case last year with the snakehead, or through an accident like a flood. Regardless, the non-native species can potentially do a lot of harm, as is the case with snakes in Guam that are decimating native species.

While I'm far from a Luddite on such issues, the first rule should be "first do no harm."