That seven-page letter set Africa in the cross-hairs of the new administration’s ‘America First’ trade ideology, pitting the world’s largest economy against tiny Rwanda over an unlikely U.S. export: cast-off clothes.In March, the USTR warned Rwanda it would lose some benefits under the African Growth and Opportunity Act (AGOA), America’s flagship trade legislation for Africa, in 60 days after it increased tariffs on second-hand clothes to support its local garment industry.

“The president’s determinations underscore his commitment to enforcing our trade laws and ensuring fairness in our trade relationships,” Deputy U.S. Trade Representative C.J. Mahoney said, announcing the decision.The 60-day grace period expires on May 28.But no matter the outcome, the row is fur…