The 'threat' to restart the moribund 'talks' is a ploy aimed at preventing (or at least delaying) a vote in the GA in favor of creating a Palestinian state in compliance with UN 242. In this, the US is colluding with israel to its own detriment. The US rather not deal with a new situation that will put it on a collision course with Israel. Tough luck.
Western-backed Syrian rebels say kill foreign Islamic State (Reuters)
from the article: Clinton: U.S. plans new push on Israeli-Palestinian peace