The fresh air of Canada's Rocky Mountains clears the head. It'll need to.

Here, the village of Kananaskis (population circa 130) finds itself, temporarily, the diplo-centre of the world - hosting diplomacy of the difficult kind.

If this isn't quite a crisis meeting, it's a meeting amidst crisis. The is front and centre of the G7 agenda and key players have come here talking de-escalation.

If they're speaking with a single voice at the start, don't hold your breath for a single strategy by the end.

The G7 starring is a different movie - this isn't a gathering built necessarily on the shared understanding and common purpose that has, generally, defined the annual team meeting of the world's leading democracies.

Here, an abrasive US president will schmooze leaders he's screwing on trade, undermining on defence priorities and, generally, putting at a distance.

Ukraine's and South African President - both veterans of the Oval Office hair dryer treatment - are the special guests filed under specially awkward.

Reaching any kind of common strategy on the Middle East will be difficult in the immediate term, as it is in the long-term.

Trump is a man with a different vision for the region and, without a shared view of the destination, it's complicated from the start. The same applies to Ukraine.

At this gathering, the dynamic will be all about the Donald. The centre of gravity will revolve around their US invitee, reflecting the wider picture of a world working out Trump and shaping its response accordingly.

The Canadian hosts are, reportedly, discarding the usual joint communique at the end, avoiding the potential for discord and scenes reminiscent of Trump's last G7 in during his first term, when he ripped up the agreement on his flight home.

Right down to the admin, world leaders are shifting to accommodate the president so close, and yet, so far.