The vast scale of Beijing’s high-tech balloon programme

There will no doubt be some tense moments in the boardrooms of western technology companies over the coming days after the revelation that the Chinese spy balloon shot down after traversing the United States had western-made components with English-language writing on them. The finding was reportedly contained in intelligence briefings to US lawmakers and will almost certainly lead to still greater scrutiny of the sale to China of advanced ‘dual-use’ technology.

Investigators are continuing their efforts to recover the wreckage of the balloon and its...