National security is the new cover for US protectionism. President Donald Trump signed his steel and aluminium tariffs under that false guise. But metal bending is not the most worrisome new area for protectionism. Trade in physical goods and services has been flat for years, but digital flows of commerce and information have risen by 45-fold in the past decade, according to the McKinsey Global Institute. The trade war to fear is not in physical commodities, but in technology, which economic nationalists hope to ringfence in order to stave off competitive threats from countries such as China.

The US has already launched a so-called Section 301 investigation. The results are due this summer, but it will probably result in stricter barriers on Chinese investment in American data and IT. That could shut out companies such as, say, Tencent, or result in new tariffs on a wider variety of Chinese products — or even usher in new visa rules for Chinese immigrants.

Last week, the Committee on Foreign Investment in the US announced it had launched a review into Singapore-domiciled chipmaker Broadcom’s bid to purchase Qualcomm, a leading US semiconductor business. The move followed pressure from Texas senator John Cornyn and California representative Duncan Hunter, who have each received more than $15,000 in donations from Qualcomm’s political action committee, according to Federal Election Commission records. Treasury secretary Steve Mnunchin, who chairs Cfius, said last week that the US was “fully prepared” to use its powers to prevent the deal should it threaten national security.