Oil retreated from the highest level since 2014 before President Donald Trump announces whether he’ll scrap an accord with Iran, a move that could significantly affect the OPEC nation’s crude exports.

New York futures slid as much as 1.5 percent, with Trump set to make a call on whether he’ll pull out of the 2015 deal between Iran and world powers that eased sanctions on the oil producer in return for curbs on its nuclear program. In the previous session, prices briefly slid below $70 after breaching the level for the first time in 3 1/2 years following news that an announcement would be made at 2 p.m. Tuesday in Washington.

“The most important event of the week is today,” said Naeem Aslam, chief market analyst at brokers Think Markets UK in London. “Investors will be watching Donald Trump’s decision on Iran very closely.”

The price volatility has been spurred by swirling speculation over the impending decision. While foreign officials and analysts say Trump is likely to remove the US from the pact, the president may also surprise allies by agreeing to stay in the accord a while longer as American and European diplomats forge side deals aimed at addressing his concerns.

The potential fallout in the oil market is unclear. While consultant FGE is among industry watchers that have said renewed US measures may cut production from OPEC’s third-largest member, Barclays Plc sees Iran’s output little changed in 2018. How European and Asian oil buyers deal with possible American action, as well as the effect on OPEC’s output curbs aimed at shrinking a global glut, will also be watched.

West Texas Intermediate oil for June delivery dropped as much as $1.06 to $69.67 a barrel on the New York Mercantile Exchange and traded at $70.07 as of 12.49 pm London time. The contract climbed $1.01 to $70.73 on Monday. Total volume traded Tuesday was about 10 percent above the 100-day average.

Brent for July settlement fell 64 cents to $75.53 a barrel on the London-based ICE Futures Europe exchange. Prices on Monday climbed 1.7 percent to $76.17. The global benchmark crude traded at a $5.54 premium to July WTI.

Futures for September delivery on the Shanghai International Energy Exchange rose 0.2 percent to 459.1 yuan a barrel. The contract climbed 2.6 percent Monday.