In recent years, it has become a pattern for the United States to launch anti-China measures just before major negotiations. Sure enough, ahead of a presidential summit this month, Washington put five Chinese refineries on a blacklist. Dozens of smaller Chinese shipping firms and vessel operators are already on the sanctions list as part of a campaign to squeeze Iran and disrupt its oil revenue. The latest additions include Hengli Petrochemical (Dalian) Refinery, one of the largest and most highly integrated operators. The Americans no doubt hope to gain bargaining power over China. But it has never worked, besides irritating the Chinese with their lack of diplomatic etiquette or common-sense manners.

Hengli denied doing any business with Iran. But perhaps repeating the same mistakes has become a hallmark of American foreign policy. Beijing is losing patience. In an unprecedented move, it ordered all mainland firms to ignore the US sanctions on the five refineries. While the order does not cover foreign entities, those who comply with the US sanctions can be sure Beijing will take a dim view of such actions.

Washington under US President Donald Trump seems preternaturally incapable of working out consequences or looking a few steps ahead. Rather than putting China on a spot, the US has cornered itself – it could enforce the sanctions and risk confronting China or back down and lose face. At the moment, Trump – who already postponed the summit once because of the Iran war – needs it much more than President Xi Jinping. Trump has a tendency to flip-flop. When asked in the Oval Office about the coming summit, he sounded conciliatory, calling Xi “a tremendous guy” and adding that “we do a lot of business with China”.

Countries, of course, have every right to reject unilateral sanctions imposed by a bullying America. Few, though, have the economic power or diplomatic standing to challenge Washington, which often threatens others with secondary sanctions. Even so, more countries are developing their own trade and financial systems to bypass the long arms of the US. In the last few rounds of US-imposed tariffs worldwide, China was the only country that dared to go toe to toe with Trump, leading to a trade truce that may be extended with the coming presidential meeting. That ought to have shown the US that an increasingly confident China will not compromise or comply with what it considers unlawful coercive measures. To borrow his language, Trump doesn’t have all the cards. Instead, both sides should make the most of the summit to moderate tensions between the two countries in the hope of bringing about more favourable circumstances. While few expect any breakthrough, some mutual accommodation is better than imposing sanctions.