A senior U.S. official is tamping down expectations that negotiations with Iran will result in a formal, preliminary deal this month outlining constraints on Tehran’s nuclear program in exchange for sanctions relief for the Islamic Republic.

The official says the two sides are aiming only for “an understanding that’s going to have to be filled out with lots of detail” by their late March target date.

The official demanded anonymity because this person wasn’t authorized to discuss the secret negotiations publicly.

This official says Wednesday that President Barack Obama will then determine whether the progress report is grounds to continue talks aimed at a comprehensive deal in June.

The official said the next round of talks is set for March 15. SAPA