Oil posted a weekly decline as the escalating U.S.-China trade war and swelling American stockpiles overshadowed tanker attacks in the Middle East.

Futures settled up 0.4% in New York on Friday but still closed the week down 2.7%. London-traded contracts slid for a fourth straight week. The White House blamed Iran for tanker attacks near the Strait of Hormuz, the biggest global choke-point for oil flows. Meanwhile, the International Energy Agency said global supplies will swamp demand next year, further pressuring OPEC.

U.S. crude stockpiles climbed to their highest since July 2017 last week, sending futures to the lowest in almost five months. The accumulation of excess supply runs counter to seasonal trends and adds to anxiety over the demand implications of the U.S.-China trade dispute, said Bill O’Grady, chief market strategist at Confluence Investment Management LLC in St. Louis.

“We’re seeing a back-up in inventory, but what’s really crippling the market are demand concerns,” O’Grady said. “There is a negative effect for the world economy from the trade tensions.”

The market’s muted reaction to the tanker attacks may be because “there’s no way” Iran could fully halt the flow of crude through the Strait of Hormuz, said Michael Hiley, head of over-the-counter energy trading at LPS Futures in New York.

Talk Of War?

“A couple of mines on boats that are carrying things other than crude oil, is that really going to stop the flow of crude?” he said.

While a war in the Middle East would disrupt energy flows, the region is less important for global crude markets than it was a couple of decades ago due to the rise of U.S. shale production. Unless the situation escalates dramatically, the prospect of a prolonged trade war between China and America—the world’s two biggest economies—probably remains the key price driver.

West Texas Intermediate for July delivery closed up 23 cents to $52.51 a barrel on the New York Mercantile Exchange. Prices have advanced 16% year to date.

Brent for August settlement rose 70 cents to $62.01 on London’s ICE Futures Europe exchange. The global benchmark crude traded at a $9.24 premium to WTI for the same month.

U.S. officials released images that they said show Iran was involved in Thursday’s attacks on the tankers. U.K. Foreign Secretary Jeremy Hunt said the incidents posed a serious danger to the region and that it was almost certain that Iran’s Islamic Revolutionary Guard was involved.