Editorial: Any future spy balloon incursions should be downed on arrival, not on exit

​The US’s foes knew that in Vietnam, and bided their time. Osama bin Laden is said to have deduced America was soft in the 1980s.

The Afghans too took their time – 20 years – to see off the US. And China has been monitoring western vulnerabilities for decades.

This weakness is rooted in great wealth that means, for example, there are certain basic jobs that rich countries can’t get their citizens to take. And it means that civilian populations will only tolerate low numbers of military losses before pressurising politicians to withdraw from conflict.

The position is by no means helpless. Ukraine has shown that our adversaries can overstate western weakness. And, while Europe has neglected its defences, America has not, and easily retains military superiority over ever other nation.

But China, by far the greatest challenger to the existing global order, is catching up fast. It is almost as rich in absolute terms (although still far behind per capita) and it is investing vast sums in its military.

To its delight, this rise has been met with naivete in many countries. Only under American pressure did Britain refuse Huawei the rollout of 5G networks, and it has not yet fully removed Chinese input into new nuclear power in the UK.

The Chinese spy balloon was over American airspace for a week before it was shot down. The downing as it the balloon left the US was symbolic. China will already have the images that it wanted to get, and it will continue spy in other ways. But it was a calculated breach of US airspace, roaming from one sensitive site to the next.

This ruthless country rejects our core values, and rejects international norms. The next time a Chinese balloon tries such a venture, let’s hope it is spotted and shot on arrival, not on exit.