Oil risks sliding back under $60 a barrel as a surge in U.S. shipments to Asia threatens to undermine a deal between OPEC and its allies, according to ING Groep NV.

While the producer group complied with a pledge to curb output and ease a glut in 2017, U.S. flows that are gaining a bigger slice of the prized Asian market may prompt some nations to boost supplies, said Warren Patterson, a commodities strategist at the Dutch bank. The resulting fallout could drag down crude prices after a rally of more than 40 percent since June, he said.

“The longer the deal goes on, it’s going to start falling apart,” Patterson said in an interview in Singapore, referring to an output-cut agreement between the Organization of Petroleum Exporting Countries and other producers including Russia. “They continue to give market share away to the U.S.”

Brent crude, the benchmark for more than half the world’s oil, is trading near $65 a barrel, compared with about $45 in June. ING forecasts Brent at $57 in the second half of 2018. Prices were at more than $115 in mid-2014, before a global glut sparked the biggest crash in a generation. West Texas Intermediate, the U.S. marker, is currently near $62 a barrel.

Crude’s rebound since last year is encouraging American drillers to pump even as they make efforts to be disciplined on spending, Patterson said. “We need to see prices in the short-term trade below $60 to reduce that incentive for U.S. producers,” he said.

As American output continues to expand, more exports will sail to Asia, the traditional bastion of Middle East producers. In February, even Saudi Arabia’s state oil company considered participating in these flows via a U.S. unit, before determining it wasn’t economically viable at the time.

Bullish Calls

ING’s outlook is in contrast to bullish views from Royal Bank of Canada and Goldman Sachs Group Inc. to BMI Research and Societe Generale SA, which see prices supported as strong demand soaks up supply from the U.S. While Patterson does see healthy oil consumption, he said growth may slow and fail to completely absorb gaining American output.

While the U.S. is now pumping more than 10 million barrels a day, surpassing a record set in 1970, that boom is being accompanied by a surge in overseas shipments, helping drain stockpiles at the nation’s largest storage hub. Exports have averaged about 1.5 million barrels over the past six months, almost double the level in the previous six months, Energy Information Administration data show. Asia is the biggest buyer of the supplies.

OPEC should beware as U.S. shale producers are set to steal a bigger slice of the market in Asia, which consumes more oil than any other region, according to industry consultant Wood Mackenzie Ltd. Crude shipped overseas from the U.S. will soar to almost 4 million barrels a day by the mid-2020s, rivaling shipments from Iraq and Canada, it said last week.

Asia is “a market that the Middle East does not really want to give up,” ING’s Patterson said. “We think compliance is likely to slip. The deal will still officially be in place, but once we get into 2019 there’s no chance that we will see some sort of deal.”