However, important caveats exist. The first is that the deal does not allow for "intrusive" checking by international authorities that Iran is sticking to its promises. This opens the door to later disputes and differences of opinion that could lead to even worse confrontation. The second point is that it has caused grave disquiet among the Sunni kingdoms of the Gulf. Saudi Arabia in particular has shaped its foreign policy with a view to containing Shia Iran; the fear is that this will further alienate it and the United Arab Emirates from US policy in the region. US influence over its Sunni "allies" has already been shaken by the Arab Spring, and this might further lower the temperature of the relationship. Its implications would be substantial and played out over time.
The deal reveals aspects of the world view of US President Barack Obama and the political realities he faces. With a defiant Congress refusing to do its bit under a system loaded in favour of working through bipartisan consensus, the US president's domestic agenda lies in tatters. Mr Obama has perforce to turn to foreign policy to leave something tangible for history to judge him on. The way Mr Obama's mind works is clear from his administration's ability to get Syria to give up its chemical weapons and now from the progress made in bringing Iran in line with non-proliferation imperatives. As for India, other than making it easier for its oil marketing companies to deal with Iran, any global development that secures a nation's right to pursue the path of peaceful use of nuclear energy, importantly through uranium enrichment, will be good news. That is the one point on which Iran has not budged, and the nuclear haves have recognised it.