Oil prices inched higher in early trading on Wednesday as fears of further supply disruptions intensified after U.S. forces said they began striking ​Iranian military targets for the 11th straight night and Kuwait reported ‌attacks by Iranian drones.

Brent crude futures rose 0.55%, or 50 cents, to $91.51 after markets opened on Wednesday, while U.S. West Texas Intermediate crude climbed 0.36%, or 30 cents, ​to $84.64 in low-volume trading.

This comes after oil settled at a five-week ​high on Tuesday after U.S. forces struck targets in southern ⁠and western Iran, while Iran attacked U.S. facilities in Bahrain, Kuwait and ​Jordan.

The U.S. military said it began its latest strikes on Iran late on Tuesday ​in the United States, or early Wednesday in Iran. The U.S. attacks came a short while after the Kuwaiti army said its air defences were intercepting Iranian drones on Wednesday.

The ​constant trading of strikes has raised fears of further disruptions to global ​energy supplies after Yemen's Iran-aligned Houthis opened a new front in the Iran war ‌by threatening ⁠to target vessels carrying Saudi oil in the Bab el-Mandeb Strait and announcing a naval blockade of Saudi Arabia.

The Bab el-Mandeb waterway at the southern entrance to the Red Sea has become an increasingly important route for ​Saudi crude exports ​as traffic through ⁠the Strait of Hormuz has fallen sharply since a ceasefire between the United States and Iran collapsed earlier this ​month.

Separately, Pete Hegseth, the U.S. defence secretary, said the country's war ​in Iran ⁠has cost it $37.5 billion so far, an increase of nearly $8 billion since the last public estimate.

Data from the American Petroleum Institute showed that U.S. crude and ⁠distillate inventories ​rose last week, while gasoline stockpiles fell, ​market sources said. The inventory data comes ahead of official figures from the U.S. Energy Information ​Administration on Wednesday.