AS AN opening gambit in trade talks President Trump’s deployment of his warship off Chinese waters lacks subtlety. It has precedent. When, the century before last, the British navy ruled the waves Her Majesty’s fleet was pressed into service to impose the opium trade on the Chinese and enforce the privileges of the City of London’s merchant adventurers.

There are more recent incidents in which gunboat diplomacy in the service of British imperialism can be recalled. The venerable HMS Belfast – rusting away on the Thames – was the naval command vessel during the navy’s 1949 encounter with the People’s Liberation Army up the Yangtze River.

It took the communist revolution and the recovery of popular sovereignty by the Chinese people to put limits on Britain’s imperial ambitions in this corner of the globe.

As the two trade delegations square off in Beijing Trump’s message is perhaps directed less at the Chinese government — which has developed a fair sized (and state-of-the-art) armada of its own — than at his domestic audience.

It’s a paradox but, maladroit as he is, the US president has a better grasp of what moves key sections of the US electorate than many of his liberal, and neoliberal, domestic critics. Signalling that US troops will be withdrawn from bits of the Middle East might upset Hillary Clinton but it plays well in rustbelt depressed towns where joining up is one of the few chances of securing a wage, a trade and medical insurance but where dying in the service of big business is less attractive.

A more muscular stance on trade talks sends a message to the many middle Americans who live in places where capitalist globalisation has stripped out the local economy.

The US and China are in a 90-day interregnum in which the tit-for-tat tariff war is (sort of) on hold. In this period the Dow Jones – the monitoring of which people in the US are conditioned to view as more important than either changes in the climate or their blood pressure — fell by 8.2 per cent since before Christmas.

For the US business class, for speculators and market traders as much as for investors in the productive economy, the downward movement of share prices is perceived as an existential threat. Prospects for some kind of agreement may be enhanced if the Dow Jones slide incentivises Trump to meet the Chinese halfway even if only on minor or more marginal issues. Trump has a tendency to bang the drum, strike a deal more modest than his rhetoric suggests and then proclaim great victory.

No matter. The 2008-2009 crash casts a long shadow and confirms the inexorable decline of corporate capitalism’s legitimacy. The diminution of US hegemony is underway, is inevitable and is marked by myriad steps forward and back of which this episode is but one.

It is a changing world for the imperial powers. Last year the World Bank listed the world’s economies by gross domestic product. China remains the world’s second-largest economy with a GDP of $12.24 trillion, behind the $19.39 trillion for the US. The GDP gap between China and the US has narrowed. With China up from $11.20 trillion in 2017 and $18.57 trillion for the USA.

Britain is fifth behind Japan and Germany. India displaced France as the world’s sixth-largest economy although its highly financialised economy with its industry skewed towards military and aerospace makes it especially vulnerable.

China responded to this crisis of capitalist credibility by increasing domestic demand. A sensible strategy. As is Shelter’s call for the government to spend £214bn to build three million new social housing homes.