Futures in London were up 0.5% after the OPEC+ alliance agreed to a plan to slash production by 9.7 million barrels a day starting in May. The group reached a deal following days of intense negotiations after Mexico declined to endorse the original agreement reached Thursday.

The U.S., Brazil and Canada will contribute an additional 3.7 million barrels in nominal production cuts as their output declines, and other Group of 20 nations will cut 1.3 million more. The G-20 numbers don’t represent real voluntary cuts but rather the impact that low prices have already had on output, and they would need months, or perhaps more than a year, to take effect.

Saudi Aramco reduced pricing for all its grades to Asia, signaling the state company’s intention to defend sales in its biggest market even while paring output.

“The global market remains very oversupplied, and Aramco is still prepared to fight for its market share,” said Ole Sloth Hansen, head of commodities strategy at Saxo Bank A/S in Copenhagen.

Brent for June delivery was 15 cents higher at $31.63 a barrel on the ICE Futures Europe exchange as of 2:45 p.m. in Dubai. The contract jumped as much as 8%, or $2.51, earlier in the day. It lost 7.7% last week and has fallen from $66 at the end of last year.

West Texas Intermediate for May delivery was trading 1.1% higher at $23.01 a barrel on the New York Mercantile Exchange, after dropping almost 20% last week.

Futures markets were closed on Friday, so Monday’s pricing reflects the change in values since the end of trading on Thursday, before the G-20 meeting had started.

Oil prices have been in freefall since the middle of February as some of the world’s biggest economies went into lockdown to try and stop the spread of the coronavirus. Whether the OPEC+ deal will be enough to steady a market where demand losses may be as much as 35 million barrels a day and storage space is rapidly running out remains to be seen. Goldman Sachs Group Inc. called the agreement “historic yet insufficient.”

The voluntary reductions by OPEC+ would only lead to an actual 4.3 million barrel a day cut in production from first-quarter levels, assuming full compliance by core-OPEC and 50% by other participants in May, Goldman said in a note. The bank sees demand losses in April and May averaging 19 million barrels a day.

“The scale of production cuts is a move in the right direction, but considering how badly demand is affected, it was never going to be significant enough to push the market closer to balance,” said Edward Bell, senior director for market economics at Emirates NBD PJSC in Dubai.

Traders may be skeptical that producers will make such deep output cuts, Bell said. “Is Russia going to cut production by 2.5 million barrels a day in two weeks? That’s a pretty steep ask.”

Mexico will reduce output by 100,000 barrels a day, after rejecting its 400,000 barrel-a-day share of the original deal. President Donald Trump helped broker a compromise that allows the Latin American nation to count some of the U.S. market-driven supply decline as its own.

The exception granted to Mexico may drive cracks through OPEC+ and the lack of a formal contribution from non-OPEC nations such as Canada, Norway and Brazil is also disappointing, said Vandana Hari, founder of Vanda Insights in Singapore.

The OPEC+ alliance initially met on Thursday via video conference. That was followed on Friday by a virtual gathering of G-20 energy ministers, who pledged to take “all the necessary measures” to maintain a balance between oil producers and consumers.

“This isn’t going to address the oversupply,” said Amrita Sen, chief oil analyst at consultancy Energy Aspects Ltd. “Yes it’s a historic deal, but these kinds of cuts will need to be in place for months if not a year to come anywhere close to solving the problem.”