The lukewarm response to Trump's tweet has seen global crude futures spike in Asian trade with both Brent and WTI front-month contracts jumping more than 1% to $79.88 and $71.60 per barrel respectively. Money managers' wagers on higher Brent crude prices are having their longest streak since November 2017, according to ICE Futures Europe data. The Organization of the Petroleum Exporting Countries' own estimates, according to its secondary sources such as researchers and ship-trackers, put Iranian output at 3.58 million bpd.
"While Citi is pricing in Brent (ICE) crude at around $80 for the quarter ahead, balances are precarious and the lack of spare capacity could see crude pricing well above $90 or even $100 should all of the potential risk in the market materialize", analysts including Ed Morse said in the note.
OPEC leader Saudi Arabia and its biggest oil-producer ally outside the group, Russia, on Sunday effectively rebuffed Trump's demand for moves to cool the market.
While viewing high demand as healthy, the organisation noted that the trend was fuelled by developing countries undergoing major demographic and general economic expansion.
The OPEC cartel concluded in December 2016 an agreement with non-member states - including Russian Federation - to cut output in order to keep prices from sliding. The sanctions go into effect November 5. The US president has called it a "monopoly" and urged it to "get prices down now". Opec estimates that coal usage in the OECD countries will plummet by a third by 2040, but it will increase by 20 per cent in developing countries to reach five times the volumes burned in the west.
Four gunmen ambushed a military parade Saturday, killing 29 people and injuring 70.
Iran's Supreme Leader Ayatollah Ali Khamenei blames USA allies in the region and promised "deadly and unforgettable revenge".
The market was "increasingly concerned about dwindling (U.S.) inventories", ANZ bank said on Monday.
U.S. commercial crude oil inventories are at their lowest since early 2015.
Major oil trading houses are predicting the return of US$100 crude for the first time since 2014 as OPEC and its allies struggle to compensate for USA sanctions on Iran's exports.
"Placing constraints on exports of American-made energy works against America's energy future", said API Chief Economist Dean Foreman.
"Our plan is to meet demand", he continued.