ROME — As the United States grapples with some of the most intractable problems in the Middle East, it has run into a buzz saw of criticism, not from traditional enemies but from two of its strongest allies. During stops in Paris and London this week, Secretary of State John Kerry found himself insisting that the United States was not facing a growing rift with oil-rich Saudi Arabia, whose emissaries have described strains over American policy on Egypt, Iran and Syria. And during a stop in Rome, Mr. Kerry sought to reassure Prime Minister Benjamin Netanyahu of Israel that the Obama administration would not drop its guard in the newly invigorated nuclear talks with Iran. Mr. Kerry’s comments appeared to do little to persuade Mr. Netanyahu, whose demands that Iran dismantle its nuclear program are tougher than any compromise that the United States and other world powers seem prepared […]