By Tim Lister, Frederik Pleitgen and Aida Kamiri, CNN

Commuters drive past a large billboard depicting Iran's Supreme Leader Ayatollah Mojtaba Khamenei on a street in Tehran on April 20, 2026.

Iran and the United States have signalled they are closing in on an agreement to turn the existing ceasefire that ended weeks of conflict into a more long-lasting settlement.

Both sides are talking of a "memorandum of understanding" that will set out a roadmap for resolving all outstanding issues, although a deal is not expected to be reached today.

But what is in that memorandum remains unclear.