Depending on a "US nuclear umbrella" as Turkey has done so 70 years no longer makes any sense. The american people are no longer willing to meet any of the America's foreign commitements, and that includes "nuclear umbrellas" whereever they may may supposedly be. And what goes for Turkey goes even more for South Korea, Japan and Taiwan. As far as Israel giving up its (presumed) nuclear deterrant, they would have to be some real dumb israelis to do any such thing.
Obama to meet with Jordan's King Abdullah in White House later this month (Reuters)