With WTI Crude futures topping $63, at the highest level since Dec 2014, it seems the market has convinced itself that everything is fixed thanks to OPEC, inventory overhangs are a thing of the past, and Aramco’s IPO can go ahead on its glorious fee-proving crescendo…

However, as OilPrice.com’s Tsvetana Paraskova points out, 2018 may not be as easy a year for the cartel to stick together.

OPEC and its Russia-led non-OPEC allies in the deal managed to stay together for a full year of high compliance with the oil production cuts and have agreed to extend the pact for a second year to the end of 2018.

This year, however, the cartel and friends face even more challenges in sticking together until the end of the December, with both supply and demand uncertainties adding to the unknowns.

On the one hand, within the cartel, possible production slumps from two OPEC members could trigger an early exit. Another internal OPEC factor could be the ever-present possibility that some members may cheat on the production cut deal outright now that oil prices are higher.

On the other hand, factors outside OPEC’s control, such as U.S. shale production expansion and potentially strong global oil demand growth, could also spell the end of the production pact. OPEC could see U.S. shale as rising too much and threatening to eat away at an even bigger portion of the cartel’s market share. Or some phenomenal oil demand growth, stemming from solid economic growth, could help OPEC to accomplish its mission to draw the global oil inventories down to their five-year average somewhere around the time the cartel meets to review the deal in June 2018.

There are four ways in which various political and supply/demand factors could combine to call an early end to the OPEC/non-OPEC cuts, according to Bloomberg’s Grant Smith.

1. Collapsing Oil production in Iran and/or Venezuela

Protests in Iran have been the main theme in geopolitical upside risks to oil prices at the beginning of this year. However, analysts think that immediate supply disruptions out of Iran are unlikely. But the fallout of the protests and the regime’s response to them could embolden U.S. President Donald Trump to refuse to certify the Iran nuclear deal and extend sanctions on Tehran’s energy industry, according to Helima Croft, global head of commodity strategy for RBC Capital Markets. President Trump faces several Iran-deal-related deadlines in coming weeks.