A bizarre formula, some strange inclusions and exclusions, and some allies who sought to avoid the tariffs left in the lurch.

While U.S. President Donald Trump announced tariffs on allies and foes including Europe, India, Japan and China, some of the world's most heavily sanctioned countries - Russia, Belarus, Cuba and North Korea - avoided being singled out for special punitive treatment.

Russia and North Korea were excluded from Trump's tariff list as neither country engages in meaningful trade relations with the United States.