[coloradan]

A gravity tractor is an incredibly stupid idea. For all the thrust it would take to move a massive object into an orbit near a threatening object, such that they would gravitationally interact for a more-than-fleeting length of time, all you get is the miniscule force of gravity between the two objects. Thousands or millions or billions of times more efficient would be to apply the same thrust directly to the threat object, and push it out of harm's way.

[HAL9000]

There might be an endangered species on that asteroid. We cannot interfere with it's natural habitat by changing it's trajectory.

[COUNTrecount]

Didn't Bruce Willis already take care of that "issue"?

[TomGuy]

The UN would pass a resolution.

And the US Congress would respond with a more aggressively worded non-binding resolution.

While the EU debates the issue and decries the aggression of the United States and Israel.

And Al Gore declares it a product of global warming climate change.

[vigilante2]

another excuse to raise taxes

[DCPatriot]

Bruce Willis is too old.

[Issaquahking]

Make it against the law to shoot down an asteroid. The U.N. has broke every law in the book...this would be a good one to break! LOL