Despite all the backslapping after the marathon Vienna talks, which have resulted in what appears to be a triumphal diplomatic outcome, not everyone is happy. Indeed, Iran and the P5+1 may have found the one issue on which Israel and the Arab states agree: Iran cannot be trusted.

Prime Minister Netanyahu described the deal in typically understated fashion as 'an historic mistake'. Saudi Arabia stopped short of fully endorsing the agreement, saying only that it always supported a deal 'that would prevent Iran from acquiring a nuclear weapon'. The short statement warns darkly that, should Iran incite regional turmoil, it 'would only be met with harsh and determined responses from the countries of the region'. The other Gulf states, who are smaller and who see economic potential in Iran, are likely to be more conciliatory. Indeed, the UAE was one of the first to publicly welcome the agreement, even if privately it despises it. Sunni Arab mistrust of Iranian intentions is palpable to anyone who travels in the region. It is largely the product of geopolitical rivalry, tinged with religious and ethnic bigotry.

Naturally, Obama and his team are well aware of how Arab states view the deal, and Washington has tried to reassure the Gulf state in particular that the US security guarantee remains in place. A key element of this reassurance was the US-GCC summit held at Camp David in May. The joint statement from the summit noted the GCC's strong support for the efforts of the P5+1 negotiations with Iran, but you could sense the displeasure among GCC states, with most of its leaders finding reasons not to attend the event. Still, the statement also reaffirmed US security support for the territorial integrity of the GCC, as well as advisory support for the Arab League's proposed Arab rapid response force and GCC ballistic-missile defence.

To reassure the Gulf states, Washington has also had to reluctantly adopted some policy positions. Washington has provided military support to the Saudi-led air campaign in Yemen, an operation increasingly seen as lacking any coherent campaign plan. In June the US also announced a resumption of arms sales to Bahrain, even though the State Department acknowledged that the human rights situation there remains inadequate. Although Human Rights Watch criticised the move, it too needs to be seen as part of the price Washington is prepared to pay to reassure some seriously upset regional allies.

But these travails have an upside for Washington too. Nothing says 'security reassurance' quite like advanced weaponry, and as the Arab states increasingly see their military forces as an extension of their foreign policies, demand for weapons has skyrocketed. So despite Gulf Arab disappointment with Washington; despite Saudi Arabia's flirtatious behaviour with Moscow; and despite competition from France and the UK, who market themselves aggressively in the region; it is fair to say that US arms sales to the region will largely be the means by which Washington assuages regional unhappiness with the Iran nuclear deal.