(Bloomberg) — OPEC is finally making the move that could help complete a mission that it’s failed so far: shipping less oil to the U.S., according to Sanford C. Bernstein.

Exports from the Organization of Petroleum Exporting Countries to America have declined by close to 1 million barrels a day since a peak at the end of March, Bernstein analysts including Neil Beveridge wrote in a May 25 report. The group, including top producer Saudi Arabia, understands that reducing cargoes to the U.S. is the top priority if it’s to reach the goal of shrinking a global inventory glut, they said.

OPEC is curbing its supplies just as the U.S. threatens to eat into the group’s market share in its traditional strongholds such as Asia, the world’s biggest oil consuming region. The group’s problems have also been compounded by a spike in shipments to developed nations at the end of last year, just before a six-month output cut deal with some allies including Russia went into effect in January. That means global inventories have increased rather than shrunk since the curbs were announced, according to Bernstein.

“While OPEC has been slow to act so far, it finally looks like they are starting to deliver,” Beveridge wrote. Since April, “we have seen a noticeable reduction in exports of oil from OPEC to OECD countries, with a drop of close to 1 million barrels a day. Importantly, most of the reduction in OPEC exports to the OECD has been concentrated in reductions of crude exports to the U.S.”

OPEC and its allies are meeting in Vienna Thursday to discuss prolonging their output curbs. Their goal is to reduce global inventories to or below the five-year average and revive prices from their worst crash in a generation. Futures in New York traded down 2.2% at $50.21 a barrel by 6:42 p.m. Singapore time. Brent in London slid 2.2% to $52.80, still more than 50% below its 2014 peak.

If OPEC is to reduce U.S. crude inventories back to normalized levels by the end of the year, stockpiles need to fall consistently by 5 million barrels per week for the next 30 weeks, Bernstein estimates. “This means a reduction in supply to the U.S. of close to 1 million barrels a day,” it said in the report.

While OPEC exports to the U.S. have fallen by almost that volume since the end of March, according to Bernstein, America has been shipping more to the world, including Asia. As Middle East nations including Saudi Arabia bear the majority of the mandated output curbs, the regional benchmark Dubai crude has strengthened versus U.S. West Texas Intermediate, making oil linked to WTI attractive to buyers.

U.S. oil exports to China, the world’s biggest energy consumer, surged to 768,000 metric tons in April, giving it a market share in the Asian nation of 2.2%, compared with 0.1% a year ago, according to Bloomberg Intelligence. The Middle East’s market share, meanwhile, fell to 43% from 47%.

Exports from Saudi Arabia, which “matters most,” to developed nations have significantly fallen since the beginning of April, according to Bernstein. “Saudi has been able to reduce loadings to the U.S. primarily though changes in its pricing policy, which arguably should have been more aggressive,” Beveridge wrote. “Since the start of the year Saudi has raised the price of its light crude grades to the U.S. relative to Asian delivery.”

Maintaining production and export discipline in the second half of 2017 will be OPEC’s most important priority, according to Bernstein. Assuming the group is able to do this, inventories should fall “‘noticeably” and continue to support an “upward path for oil prices,” it said.

Bloomberg News by Serene Cheong