New Delhi, July 4 -- For Vietnam, its latest trade deal with the US is a bitter-sweet outcome. While the country has managed to escape a 46% tariff that US President Donald Trump had threatened to impose on "Liberation Day" this April, its US-bound exports will still face a 20% duty.

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If cargo sent from Vietnam happens to be a trans-shipment of merchandise made elsewhere, then that tariff barrier would rise to 40%. This is a device to stop exporters from using its ports to game the US-set matrix of tariffs that vary from one country to another based on a puzzling formula.

Meanwhile, under the deal, US exporters will get "total access" to Vietnam's markets, as Trump said in a social...