Kyiv and Washington have reached a deal over Ukraine’s mineral resources, but many details remain to be worked out before any money starts flowing.The text of the deal, which doesn’t include explicit security guarantees for Ukraine,

It was not immediately clear what the sticking point was, but Ukraine is pressing for robust security guarantees from Europe and the United States that would protect it from Russia in the future if a peace deal is reached.

The BBC's Analysis Editor Ros Atkins takes a look at what we know - and what we don't - about the US-Ukraine mineral deal.