What 'security guarantees' for Ukraine would actually mean

In the wake of this week's historic White House meetings, President Volodymyr Zelensky says Ukraine and its allies are "already working on the concrete content of the security guarantees".

Sir Keir Starmer has been chairing a virtual meeting of those nations prepared to help secure Ukraine after a peace deal - the so-called "Coalition of the Willing".

And Britain has dispatched its Chief of Defence Staff, Admiral Sir Tony Radakin, to Washington to work out how the US can help. The cogs are clearly turning.

But what do "security guarantees" actually mean in practice?

There is a wide spectrum here, ranging from the much overused "boots on the ground" to the threat of crippling economic sanctions on Russia's oil exports.