Edward Luce argues convincingly that the already very high sovereign debt burden of the US will only get worse due to the current partisan politics (Opinion, May 31). He reminds us why sterling lost its reserve currency status due to its war-related debt. It is true that the war debt caused sterling’s demise. But the other significant reason for it was the ascending power of the rapidly industrialising US economy and the dollar’s accelerating claim on global trade around the early 20th century. We are witnessing a similar scenario unfold almost 100 years later: China’s aggressive claim on global trade and the resultant threat to the dollar’s supremacy.

Three conditions are necessary for another currency to upend the dollar as the world’s reserve currency: a rival must have scale (a large share of global trade), a market economy and a democracy. History shows that Britain had all three, before the dollar usurped sterling as the dominant currency.

The US still has all three of the elements, although the institutions that protect, nurture and sustain democracy are under alarming threat. China has the scale and is adopting a market economy, but it falls woefully short in meeting the principles of democracy — Beijing’s recent anointing of Xi Jinping as its quasi emperor is hardly a political path to democratise society. The EU has democracy, although its principles are challenged by Poland, Hungary and now Italy, but it does not have scale like China.