The bout of volatility that gripped financial markets last month may occur again, the chief economist of the Bank for International Settlements said, as investors are weaned off expansionary monetary policies that have been in place for many years, The Wall Street Journal reports.

Central banks face a delicate balance complicated by “the most recent protectionist rhetoric,” said Claudio Borio, chief economist at the BIS, a consortium of central banks based in Switzerland, in comments released Sunday. Last week, US President Donald Trump announced tariffs on steel and aluminium, prompting concerns that other countries may retaliate.