Yet oil markets have shrugged it all off.
"In the past such geopolitical tensions gave a boost to oil prices," says Fatih Birol, the head of the IEA.
The price of Brent crude has subsided from a high of nearly $75 in April to around $60 today.
One reason is that America's frackers have continued to pump more oil.
The country's daily output in September was 12% above last year's average.
It is also because economic growth has slowed, with oil demand suffering not just in Japan
but in India and South-East Asia, where it was expected to grow strongly.
Next year economic growth may tick up. Investors are pressing American shale companies to reduce spending and boost profits.
That would result in flatter production and, in turn, help nudge prices higher.
But new supply elsewhere looks set to push prices in the other direction.
ExxonMobil is ramping up production off the coast of Guyana.
Brazil's attempt to auction new offshore leases this month was a failure—supermajors, such as ExxonMobil and BP, declined to bid.
Yet investments already made offshore mean that by 2021 Brazil's crude production may be 18% higher than this year, according to IHS Markit.
Norway will also see a surge in output.
Notwithstanding its announcement in October that its sovereign-wealth fund
would sell its holdings in oil exploration and production companies,
the country itself is expected to increase production markedly in the coming years.
Its state-backed energy giant, Equinor, said in October that Johan Sverdrup, a giant new oilfield in the North Sea, had begun producing crude.
The broadened OPEC alliance must now decide whether to hold at the reductions agreed to last year, or to cut harder.
The current arrangement may be insufficient to keep Brent crude above $60 a barrel.
Yet there may be little appetite for dramatically lower production targets.
Aramco, Saudi Arabia's state-backed oil company, plans to list some of its shares in mid-December, shortly after OPEC's meeting.
Any agreement for a big cut in the kingdom's output would lower estimates for Aramco's earnings,
which would suppress its valuation, points out Neil Beveridge of Bernstein.
On the other hand, he says, "the worst thing that could happen to Aramco would be to see the listing go ahead and see the oil price collapse."
This has been a dramatic year on oil markets. December could bring further plot twists.