New Delhi, Aug. 20 -- With Donald Trump in charge, one never knows which way America would go until the last minute. That unpredictability was on show late Tuesday. Just a few hours before a punitive tariff the US President had threatened to slap on Canada was to go into force, he deferred it.

And for how long? A grand three days. Trump cited a deal being close with Ottawa for the postponement of the 50% levy. His use of tariffs as bargaining chips has been apparent to all.

Spare a thought, however, for the US Customs and Border Protection, a federal agency that charges import duties. Even in a world of communication instancy, it must surely be a nightmarish task.

From a larger lens, this sort of back-and-forth, a cadence that seems in...