For those staring into the vast chasm that is the gap between the US and China on trade that was laid bare on Friday and looking for hope, there was really only one thing to seize on. US president Donald Trump has laid out extreme demands and promised extreme responses before. Yet, in his almost 16 months in office, he has so far only rarely delivered them.

The best — and most-cited — example of that so far on trade lies in his repeated, and so far undelivered, promises to rip up the North American Free Trade Agreement. As ministers from the US, Canada and Mexico gather in Washington on Monday for what is being billed as (another) final push to strike a deal, it is worth asking if the comparison between Trump v China and Trump v Nafta is worth contemplating.

The comparison implies that, as he has in Nafta, Mr Trump might bob and weave and eventually bend in pursuit of a grand bargain. Yet it is probably not entirely constructive. Here are three reasons why: