Earlier this week Keir Starmer said that he was ready and willing to send British troops to Ukraine to help guarantee its security, should there be a ceasefire.

But so far he too is unclear as to what they might be asked to do.

In terms of numbers of troops that might be needed, Brigadier Watson said “clearly what the force package would look like would be dependent on what the prime minister and the Ministry of Defence would like”.

But he said “it’s absolutely not” something the UK could do on its own. “I think the prime minister has been very clear that the UK would contribute to efforts, but absolutely not doing it on our own,” says Brigadier Watson.

Exercise Steadfast Dart is Nato’s largest exercise this year and meant to demonstrate how quickly allies can come to the defence of an ally under attack. But while it’s meant to demonstrate Nato’s readiness, it also highlights its limitations too.

The UK has shown it can move large numbers of troops and equipment, including more than 700 military vehicles, 1,400 miles (2,253 km) across Europe at relatively short notice as part of Nato’s new Allied Reaction Force.

And that it can operate alongside allies. More than 10,000 military personnel are taking part in the exercise from eight European nations.

But that is just 10% of the number that most military experts believe might be required for any peacekeeping operation inside Ukraine which might require a force of more than 100,000.