US undermining another international treaty

Not content with "unsigning" the Rome Treaty on the ICC, withdrawing from the ABM Treaty, and undermining Kyoto, the US is now setting its sights on the Montreal Protocol.

The Montreal Protocol is one of the more successful international environmental agreements. It's been responsible for the phasing out of ozone-reducing chemicals in much of the world, giving the ozone layer a chance to recover and preventing untold cases of cataracts and skin cancer. But now the US is trying to wreck it by pushing for special exemptions so it can continue to pollute while others cannot. Why? Because its cheaper, of course!

Why does anybody bother to sign treaties with the United States anymore? It's clear that, under Bush, the US no longer stands by its word. It will happily sign a treaty, then renege on it six months (or sixteen years) later; "unsign" treaties with no withdrawl cluase; or simply reinterpret things so the US can continue to do whatever the hell it wants (at the same time demanding that others stick to what they originally signed up for). With a "partner" like this, why even bother with an agreement in the first place?