Global stock markets extended a severe plunge Monday, fueled by fears that U.S. tariffs would lead to a global economic slowdown.

European and Asian shares saw dramatic losses, the leading U.S. index flirted with bear market territory in pre-market trading, and oil prices sagged.

The massive sell-off in riskier assets at the start of the trading week follows President Donald Trump’s announcement of sharply higher U.S. import taxes and retaliation from China that saw markets fall sharply Thursday and Friday.

Late Sunday, Trump reiterated his resolve on his decision to introduce tariffs of 10 per cent to 50 per cent on goods imported into the U.S.

The move is seen as massively disrupting world trade and supply chains across borders.

Speaking to reporters aboard Air Force One, he said he didn’t want global markets to fall, but also that he wasn’t concerned about the massive sell-offs.

Presdient Trump added: “Sometimes you have to take medicine to fix something.”