None of the countries targeted in the first batch of letters — the Philippines, Brunei, Moldova, Algeria, Libya, Iraq and Sri Lanka — is a major industrial rival to the United States.

Brazil is set to summon the U.S. embassy's chargé d'affaires after the diplomatic entity backed ex-leader Jair Bolsonaro. This comes as Trump, via social media, labeled Bolsonaro's trial for an alleged coup plot a 'witch hunt.

For the third time in three months, Donald Trump has identified a foreign ally facing legal trouble. And also for the third time in three months, the American president has condemned the foreign case as a “witch hunt.