First, I find it hard to believe that the Abbas move was aimed against the US. The US is potentially a great supporter, as it is for Egypt and Jordan, and it is better not to attack it directly. Perhaps Abbas wanted to go slow, giving the US and Quartet a chance to see what is coming and therefore apply needed pressure on Israel to negotiate peace while freezing settlement construction, a very elementary requirement. So far, they failed to do so, but are still working hard at a compromise. If Israel finally bends to the demand, Abbas can suspend his UN move until next year to give talks a chance.
Suspected assailant in car-ramming attack in West Bank shot (Haaretz)