Found an article on the Russo-Saudi breakdown:
https://www.ft.com/content/d700b71a-6122-11ea-b3f3-fe4680ea68b5

Saudi Arabia had last week sought the support of Opec and allies outside the cartel, such as Russia, for a substantial cut in production to stabilise the oil market, which has been reeling as the spread of coronavirus hits the global economy and saps demand for crude. But Russia torpedoed the plan, eyeing an opportunity to hit US shale producers, infuriating the kingdom and resulting in the countries removing all restrictions on their output from April. “Opec and other countries including Russia couldn’t get an agreement. If others will push their production, why is Saudi Arabia not doing the same,” said a second person familiar with the kingdom’s output policy. “Now we have the right to sell more to compensate for any loss in prices.”
Russia has built up a $170bn national wealth fund from excess oil revenues in recent years and believes it can tap that to offset any short-term price war, despite crude plunging close to its budget break even price of around $42 a barrel. Mikhail Leontiev, press secretary for Rosneft, Russia’s largest oil producer, said that the relationship with Saudi Arabia had become “meaningless”. “The true result of the arrangement is that the total volume of oil that was reduced as a result of the repeated extension of the Opec+ agreement was completely and quickly replaced in the world market with American shale oil,” he said in a statement to state-owned news agency TASS. Rosneft is majority owned by the Russian state and run by one of president Vladimir Putin’s closest and longest-serving associates. “The proposal that was made was not a partnership. A partnership agreement always implies a compromise,” Mr Leontiev said, adding that the collapse of the agreement allows Russia to concentrate on monetising its crude resources.
The last price war in 2014 upended the global oil industry, inflicting pain on producers from the North Sea to North Dakota, and forcing them to adapt to the decisive end of the $100-oil era. Higher output from Saudi Arabia would again hit the US shale sector, the rapid growth of which over the past decade has made the US the world’s top producer and forced rivals to restrict output in a bid to prop up the price. The US shale industry has struggled to generate consistent profits, however, and is struggling with tighter access to financing, leaving it vulnerable.
But the kingdom appears to be targeting Russia in particular. Saudi Arabia is set to announce that it will sell its crude into north west Europe, a key market for Russian barrels, at discounts to its reference price of more than $8 a barrel compared to March, according to an official price list seen by the Financial Times. In the US it is also set to discount its crude by around $7 a barrel in April compared with March. It also made prices cuts to Asia of between $4-6 a barrel. Monthly price adjustments are normally only a few cents or at most a dollar or two, leaving little doubt over what the kingdom is hoping to achieve. Saudi Arabia’s 12m b/d production capacity has largely been restored after the drone and missile strikes on its key facilities in September. The kingdom maintains the most spare production capacity globally, allowing it to raise its output faster than rivals. The move will put pressure on Saudi Arabia’s allies in the Gulf like the UAE and Kuwait to cut their prices and potentially increase output to remain competitive.