OPEC used to shift world oil markets with a single announcement. These days, the Saudi-led organization needs help from some key partners — most significantly Russia — to exert that kind of influence.
The expanded alliance, which also includes Kazakhstan, Mexico and other nations, is known as "OPEC+." And on Monday and Tuesday, OPEC+ made its unofficial expansion a little more official.
Member and non-member states have agreed on a "Charter of Cooperation" to formalize their relationship, pending approval from individual governments.