Simultaneously, Saudi Arabia said through its state-owned press agency that Riyadh and Moscow had held talks in Buenos Aires about “rebalancing” the oil market. While both talked about progress and extension of the cooperation, neither the Russian nor Saudis made any formal declaration about output volumes.

“This might be the critical breakthrough for OPEC and non-OPEC to cut,” said Derek Brower, a director at consultant RS Energy Group. “But the details are now what matter – how much will be cut, from when, for how long and, crucially, from what baselines.”

Earlier this week, an advisory group to OPEC told ministers the market is oversupplied, with a need to cut about 1.3 million barrels a day from October levels. The advisory group’s proposals aren’t binding, and OPEC ministers often choose a different path. Yet the view that the oil market is oversupplied is a signal the cartel is laying the groundwork for action.

OPEC, which pumps four-in-ten barrels produced worldwide, will convene in Vienna on Dec. 6 to discuss output cuts after oil prices in November suffered the largest monthly drop since the global financial crisis in 2008.

Brent crude, the global benchmark, is down about a third from an October high due to rising supply from the U.S. shale regions, Saudi Arabia and Russia, slower demand growth and American waivers on oil sanctions on Iran. Brent hit a a 4-year high of $86.76 a barrel in early October before slumping to $58.71 Friday. Oil trading has been volatile over the last week as traders took positions ahead of the OPEC gathering.

“Markets think there will be some sort of a cut,” said Mike Wittner, head of oil market research at Societe Generale SA. “However, there’s concern that the cuts will not be big enough and also that the message may be intentionally unclear, in order not to get President Trump upset.”

In public and private, Trump has told the Saudis he wants cheaper crude, even disclosing that he berated the crown prince in an October phone call when international benchmark Brent surged above $80. Prior to the collapse in oil prices, the kingdom was responsive to Trump’s demands. Its November production surged to an all-time record above 11 million barrels a day as prices swooned, prompting a jubilant response on Twitter from the White House.

For bin Salman, the kingdom’s crown prince and day-to-day ruler, the dilemma between keeping the U.S. president happy and having an oil price that balances the Saudi budget has been sharpened by the murder of journalist Jamal Khashoggi. Despite pressure from angry senators and other Washington power players, the Trump administration has maintained its support for the Saudi leader.

Putin and the prince ended years of animosity between the world’s two largest oil exporters in 2016 and have worked together since then in a deal known as the OPEC+ group, that includes the cartel plus non-OPEC members such as Russia, Mexico, Azerbaijan and Kazakhstan.

— With assistance by Grant Smith