Analysts had little hope that opposition to the United States action would prevent sanctions from going ahead.
They expect West Texas Intermediate, the most commonly cited United States contract, to trade $6 below the price of Brent in 2019. Some of that oil now will be pulled from the market, experts project.
Mr Ng suggested that these triggers are significant enough to even tilt the oil market "into deficit". He said for instance that between the two large caps, Sembcorp Marine, seen as a "pure" O&G-related play, booked a higher percentage point gain compared to Keppel Corp, which boasts a multi-business portfolio not restricted to just within the O&G industry.
The reapplication of USA sanctions - particularly if effective - likely marks the practical end of the supply cut agreement as OPEC operates through unanimous decision-making, and Saudi and Iranian oil market interests will grow increasingly divergent. The US has increased its production very much in recent months or the previous year, with rising oil prices it has become much more profitable for US oil producers to increase their production; so there's a lot of countries that would benefit from these higher oil prices.
For a start, President Trump's announcement has put hundreds of barrels of crude supplies at risk.
Crude prices swung wildly in recent days, as investors anticipated U.S. President Donald Trump's decision on Iran. Sharp declines in its Iranian crude imports are likely over the coming months. Prices had already been rising as a strong global economy has kept demand high for gasoline and other refined products. "Importantly, Iranian compliance with its JCPOA obligations may potentially help it find alternative routes to export crude oil to global markets", Barclays says. Richard Nephew, senior research scholar at Columbia University's Center on Global Energy Policy, added that China and India may continue to buy Iranian oil even in the face of USA sanctions, negating some of their impact.
UOB Kay Hian equity analyst Foo Zhi Wei countered however, that the global community may try to salvage the Iran nuclear deal.
Iran re-emerged as a major oil exporter in 2016 after global sanctions against it were lifted in return for curbs on its nuclear program.
Brent for July settlement added as much as 0.8 percent to $77.82 a barrel on the London-based ICE Futures Europe exchange before trading at $77.81.
All eyes are therefore on Opec's next move, though Mr Tonhaugen warned that the cartel is not expected to ramp up output or exports in the near future.
"Oil's always prone to rise on geopolitical tensions and the ongoing conflict between Iran and Israel is not something that can be resolved in the short-term", Will Yun, a commodities analyst at Hyundai Futures Corp., said by phone in Seoul.
Saudi Arabia said it would work with other producers to lessen the impact of any shortage in oil supplies.