Trump said on Monday that the US would impose 25 per cent tariffs on Tunisia, Malaysia and Kazakhstan; 30 per cent on South Africa, Bosnia and Herzegovina; 32 per cent on Indonesia; 35 per cent on Serbia and Bangladesh; 36 per cent on Cambodia and Thailand and 40 per cent on Laos and Myanmar.

The duties threatened in the letters effectively match the initial reciprocal tariffs Trump briefly imposed on the countries in April.

The president said at least seven countries would receive letters regarding their new tariff rates on Wednesday.