It was certainly an historic moment.

Coralling nearly 30 world leaders into the same meeting - even a video call - is an achievement whatever the subject of discussion.

And managing to coax Giorgia Meloni, who has reportedly been prickly towards the idea of a European peacekeeping force in Ukraine, into joining the call is quite impressive.

They agreed to more sanctions if Vladimir Putin won't play ball. And they discussed moving military planning to an operational phase - planning how nations will work together in the event of an actual deployment.

But whether the outcome of the meeting will be consequential in the grand scheme of the conflict in Ukraine remains to be seen.

Of course, we have to hope for the best.

But Putin has yet to agree to an unconditional ceasefire.

And as I said in my question to the Prime Minister at this afternoon's press conference, there’s a possible - even likely - scenario where Putin doesn’t come to his senses.

A scenario were he won’t let go of the unreasonable demands he’s attached to a ceasefire. Where he makes the same unreasonable demands at the negotiating table.

Or, where he refuses to come to the table at all.

And if any of those scenarios come to pass, we can’t be sure Donald Trump will take our side and not Russia’s.

So what’s plan B?

It seems unlikely so many of the world’s leaders came together to discuss Ukraine and only talked about the best case scenario.

There must have been some discussion about the nightmare - where the war in Ukraine doesn’t wind down, it ramps up.

Where Trump, in a bid to save face from the failure of his ‘plan for peace’, declares Zelensky is again being intransigent and resistant to compromise. That he doesn’t really want peace. So he rows in behind Putin.

And where, heaven forbid, Putin is willing to take the fighting beyond Ukraine.

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So what is plan B? Starmer gave a hint.

“We need to put Ukraine in the strongest possible position for whatever comes next," he said. "Whether that's around the table, which is what I hope it will be, or if that doesn't come to pass."

He added: "We need as many countries as possible thinking together, discussing together and moving forward together as a group, which is what we've achieved this morning."

Light on detail - of course - but a reassuring indication, at least, that while we hope for the best, we’re preparing for the worst.