As poor nations struggle to get their hands on COVID-19 vaccines, a thinly populated South American country finds its chances linked to its unexpected role in growing tensions between the U.S. and China.

Paraguay’s 63-year-old alliance with Taiwan — forged when both were run by right-wing authoritarians — means the government can’t directly buy from China’s vaccine-makers that have supplied other Latin American nations. Officials say they’ve been approached to switch allegiances to Beijing to get the doses.

U.S. Secretary of State Antony Blinken phoned President Mario Abdo Benitez to stiffen his spine against such a shift. That led Foreign Minister Euclides Acevedo to speak frankly this week to Washington and Taipei.