The ongoing blockade of the Strait of Hormuz remains the dominant market driver, says Elias Haddad at market analysis firm BBH.
The Dow Jones Industrial Average rose 0.3 percent, but the broad S&P 500 index fell 0.1 percent and the Nasdaq Composite fell 0.5 percent.
No peace agreement is yet in sight between the US and Iran - nor is there any end to Tehran's blockade of the Strait of Hormuz, through which around a fifth of the world's oil normally passes.
Investors are concerned that the already high inflation in the US will rise further due to the surge in oil prices.
North Sea oil is now priced at $108.9 per barrel after fluctuating during the day. Before the war, it was around $70 per barrel.
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