Oil prices fell through the floor in early trading Monday, tanking as much as 30% after Saudi Arabia slashed its crude prices for buyers. The kingdom is reportedly preparing to open the taps in an apparent retaliation for Russia's unwillingness to cut its own output.

"This has turned into a scorched Earth approach by Saudi Arabia, in particular, to deal with the problem of chronic overproduction," John Kilduff, founding partner of Again Capital, told CNBC. International benchmark Brent crude was trading at $33.79 a barrel — down almost 50% year to date — at 10:45 a.m. Singapore time, with West Texas Intermediate at $30.72.

The U.S. benchmark commodity is on pace for its worst day since January 17, 1991, when it lost 33%, and its second-worst day ever. That was during the Persian Gulf War.

Experts are now calling dramatically lower crude prices as major OPEC and non-OPEC producers ready for an all-out price war after failing to reach an output cut agreement Friday, in a sudden U-turn from previous attempts to support the oil market as the new coronavirus hammers global demand.

"$20 oil in 2020 is coming," Ali Khedery, formerly Exxon's senior Middle East advisor and now CEO of U.S.-based strategy firm Dragoman Ventures, wrote Sunday on Twitter. "Huge geopolitical implications. Timely stimulus for net consumers. Catastrophic for failed/failing petro-kleptocracies Iraq, Iran, etc - may prove existential 1-2 punch when paired with COVID19."

The comment came as oil prices are down 48% for the year and two days after Saudi Arabia announced massive discounts to its official selling prices for April, between $6 to $8 lower per barrel across all regions. Plunging price forecasts are also coming amid reports of a possible increase in production by the OPEC kingpin from its current 9.7 million barrels per day (bpd) to as many as two million bpd more.

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With previously agreed OPEC+ production cuts expiring at the end of March, Saudi Arabia can theoretically pump as much as it wants — up to its capacity of 12.5 million bpd. And Russian Energy Minister Alexander Novak said Friday that essentially the wheels come off next month: "As from 1 April we are starting to work without minding the quotas or reductions which were in place earlier," he told reporters at the OPEC+ meeting in Vienna, adding, "but this does not mean that each country would not monitor and analyze market developments."