Will a trade deal be reached between the US and China? At present, we cannot be sure. The obstacles are high. But far bigger questions arise. Would a deal, if reached, stabilise conditions for trade between the two superpowers? Would stabilising those conditions ensure co-operative relations between China and the US? The answer to both questions is no. A deal would not even mark the end of the beginning of US-China frictions. It would be just a small step towards redefining this relationship.

The envisaged deal has several elements. The first is huge Chinese purchases of US-made products, in an effort to satisfy Donald Trump’s obsessive desire to eliminate the US deficit in bilateral trade. The second is liberalisation of access to the Chinese market for US goods and services. The third is reform of Chinese industrial policy, especially of “forced transfers” of intellectual property. The last is that the US must be judge, jury and executioner of the agreement. Thus Robert Lighthizer, chief US negotiator, insists on a unilateral US right to impose punitive tariffs, in the event of supposed Chinese violations, but a renunciation of retaliation or recourse to the World Trade Organization, in response.

It would be remarkable if China were to accept and abide by such humiliating terms. But suppose it did. What would follow? The most obvious point is that the US could reimpose, raise or add new trade barriers, at will, without retaliation. The incentives for the US are clear. Whenever an American interest complained about something China is actually (or allegedly) doing, the political costs of penalising the Chinese would be thought negligible. Action will then be frequently taken. In consequence, the trade policy of the US towards China would be highly unpredictable. Preventing such behaviour is why WTO rules call for tariffs to be bound and applied on a non-discriminatory basis.