Middle East stock markets tumbled Monday as they struggled with the dual hit of the United States' new tariff policy and a sharp decline in oil prices, squeezing energy-producing nations that rely on those sales to power their economies and government spending.

Benchmark Brent crude is down by nearly 15% over the last five days of trading, with a barrel of oil costing just over $63. That's down nearly 30% from a year ago, when a barrel cost over $90.