Oil prices climbed after a report said the White House has asked the Pentagon to draft options for strikes on Iran that could be carried out before the midterm elections, compounded by storm-related shutdowns of some U.S. crude production.

West Texas Intermediate rose to around $89 a barrel, while Brent settled near $100 a barrel.

The report, citing two administration officials, runs counter to the widespread market assumption that President Donald Trump would avoid escalating conflict with Tehran before next month's elections.

It said the scale and targets of potential strikes, and whether Washington would carry them out, are still under discussion.

The report added that if limited strikes were taken, a broader campaign could follow after the midterm elections.

Meanwhile, data from the Bureau of Ocean Energy Management showed that Gulf of Mexico crude producers shut in more than 510,000 barrels per day of output, about a quarter of the region's production, due to Tropical Storm Isaias.

Isaias is expected to strengthen into a strong Category 2 hurricane in the coming days.