Oil prices rose by more than four percent on Friday and reached their highest level since mid-June.

Brent crude rose 4.6% to $88.10, and West Texas Intermediate crude closed up 4.5% at $82.49. Accordingly, both benchmarks have increased by about 16% this week.

The driver of this surge was the intensification of attacks between the United States and the Islamic Republic and the renewed disruption to oil flows through the Strait of Hormuz; the waterway that, before the war, carried about 20% of the world’s oil.