From bromance to break-up: 4 ways the OPEC deal could end early

Russian President Vladimir Putin could heed pressure from his country's biggest oil companies for a swift exit

OPEC and Russia have surprised the industry with the success of their grand alliance as oil surges to a three-year high. As the unlikely bond enters a second year, there are challenges ahead.

Here are four scenarios that could end their deal earlier than planned.

Street Fighting

Tension is flaring in OPEC members Iran and Venezuela, the two countries that RBC Capital Markets LLC says pose the biggest risk of supply disruption. If either nation shuts oil output as a result, fellow producers could just decide the restraints are no longer appropriate, and instead boost supplies to prevent a damaging