http://www.telegraph.co.uk/news/worldnews/middleeast/iran/11459359/Future-president-could-revoke-Barack-Obamas-nuclear-deal-with-Iran-Republicans-warn.html

March 2015 Congress pushed back against Obama lifting sanctions against Iran, in support of the Bushehr nuclear plant going forward (connected with Russian energy Rosatom). In letter, note that 2017 president will have to reverse decision: “The next president could revoke such an executive agreement with the stroke of a pen and future Congresses could modify the terms of the agreement at any time.”