Forget for a moment how many bushels of soyabeans China will promise to buy from American farmers. Leave aside China’s expected vow to stop its theft of US intellectual property. Such pledges will buoy the markets when Donald Trump and Xi Jinping finally unveil their deal.

The radical part is the way in which they have agreed to hold each other to account. Unlike trade deals signed under Mr Trump’s predecessors, this one calls for no third parties to be involved. Each country will be licensed to decide when the other is in breach. Having sought a reset with China, Mr Trump would be enshrining a diet of endless tit-for-tat. If ever there was a blueprint for bilateral instability, the coming US-China deal would qualify.

But that is only half the story. The other is what the compact will do to everyone else. When the world’s two largest economies agree to settle disputes between themselves, the World Trade Organization is instantly sidelined. As it is, the WTO no longer accepts new cases because the Trump administration is blocking a quorum on its appeals body. Now it will be relegated to a bystander.