Investing.com - Oil price gains have accelerated after the U.S. State Department demanded earlier this week that all countries stop imports from Iran from November.
The move is part of the U.S. strategy to squeeze Iran over its nuclear program and the expected disruption to global supply has boosted prices.
But this is not the only factor driving oil prices higher.
OPEC agreed to increase production last week, but the cartel didn't agree to as big an increase as the markets had been expecting.
Also in the mix are a supply disruption in Canada, shrinking production by Venezuela, falling U.S. crude stocks and uncertainty over Libyan exports.
The recent increase in oil prices has eroded the benefit to consumers of the tax cuts passed by Republicans late last year.
In the second half of the year, focus is likely to shift to supply figures and concerns over spare production capacity as markets weigh uncertainties about the long-term outlook for oil.
Analysts are concerned that declining stocks and low availability of spare capacity could limit the ability of the oil market to absorb any unexpected supply disruptions.