And now, Bloomberg has the stunning backstory behind Friday's announcement that Russia is quitting its output deal with OPEC and its allies, after last week's Vienna summit meant to back a proposal by oil producers to cut output collapsed, causing a 10% plunge in oil prices, with some markets seeing their biggest one-day falls since the financial crisis. 

Driving a stake right through the heart of his former OPEC colleagues, Russian Energy Minister Alexander Novak said that "considering the decision taken today, from April 1 of this year onwards, neither we nor any OPEC or non-OPEC country is required to make (oil) output cuts."