Huge Chinese lending to Africa has created a dilemma where China will struggle to recoup its money while maintaining its image as a friend to developing nations, researchers at Chatham House said.

Africa’s external debt rose fivefold to $696 billion between 2000 and 2020, with Chinese lenders accounting for 12% of that, according to a new report by the London-based think tank.

While Chinese lending to Africa has been criticized by the U.S. and other Western nations as opaque and designed to seize African assets offered as collateral, the researchers said this isn’t the case.