FILE PHOTO: U.S. President Donald Trump and China's President Xi Jinping meet business leaders at the Great Hall of the People in Beijing, China, November 9, 2017. REUTERS/Damir Sagolj/File Photo

HONG KONG (Reuters Breakingviews) - China is exhibiting some worrying trade war restraint. A popular nationalist tabloid suggested this week that Beijing could retaliate against Washington using the country’s grip on rare-earth supplies, U.S. debt or American business on the mainland. A better question is why these weapons, some of which have been deployed in the past, sit idle. It points to a different, and more dangerous, conflict.

The timing of the Global Times article is, of course, intentional. It comes during a sharp escalation of tensions after U.S. President Donald Trump this month hiked tariffs and launched a fresh assault on telecom equipment maker Huawei. It’s also not the first time the jingoistic publication has implied payback.

Even so, it raises a good question. Despite plenty of bazookas in its arsenal - not least the fact China is the largest holder of U.S. government debt, to the tune of more than $1 trillion - Beijing has been reluctant to use them.

It’s all the more surprising because many are tried and tested. A dispute with South Korea saw significant damage to Lotte Group, which eventually opted to put retail stores there for sale. A flare-up with Japan may have been behind the withholding of rare earths, a key ingredient in tech products.

Officials have yet to pummel the likes of Apple, however, or engage in other dramatic and unorthodox measures.

In part, it’s because some of the options present the potential for self-harm – as with a massive selloff of U.S. debt. But Chinese officials also appear to have concluded this is not a normal fight. More conservative Chinese voices have long suspected that it is, in a sense, not really about their behaviour at all. They argue the ultimate goal is to force American outfits to move production out of the People’s Republic, and to “de-couple” the two economies.

That would explain why Beijing has been loathe to go nuclear, preferring a calibrated tit-for-tat response. Harsh retaliation would simply give more hawkish voices in the Trump administration an excuse to further ratchet tensions, or prompt companies to look for the exits.

That calculus may yet change. But so far, Beijing appears to have concluded it is better off leaving its usual weapons in storage.