LAUSANNE, Switzerland — Iran and the six world powers (the five permanent UN Security Council members plus Germany, or P5+1) could be poised to reach a political understanding on a final Iran nuclear deal by March 31, if they are able to overcome two core issues still under discussion here.

They involve the scope of research and development that Iran could conduct in years 11-15 of a final accord, and what happens on UN Security Council sanctions, according to a senior US official.

The aim this round, as the last foreign ministers from the P5+1 arrived in Lausanne on March 29, is to reach a political understanding on major parameters of a joint comprehensive plan of action, but it will not be written here, the US official, speaking not for attribution, said.

Read more here

This article was written by  Laura Rozen  for Al-monitor on March 30, 2015. Laura Rozen reports on foreign policy from Washington, DC, for Al-Monitor's Back Channel. She has written for Yahoo! News, Politico and Foreign Policy. On Twitter: @LRozen