Oil extended gains as the US said it had begun a new wave of strikes against Iranian military installations on Wednesday, aiming to limit Tehran's ability to strike commercial shipping in the Strait of Hormuz.
Washington had earlier reimposed a naval blockade of Iranian ports and launched overnight strikes, prompting Iran's Islamic Revolutionary Guard Corps to threaten to close "all other export corridors that benefit the US and its allies."
Brent futures gained 18 cents, or 0.2%, to $84.91 a barrel at 1214 GMT. West Texas Intermediate futures rose 26 cents, or 0.3%, to $79.60 a barrel.
Oil prices settled up 2% at a one-month high on Tuesday as attacks exacerbated a supply disruption in the Strait of Hormuz, through which about a fifth of the world's oil and liquefied natural gas passed prior to the war's outbreak.
The hostilities between Iran and the US reignited last week, fraying an already fragile truce reached in June after several months of fighting.
Late on Tuesday, the US military said it had hit dozens of military targets near the strategic waterway and Iranian coastal areas in strikes lasting seven hours.
In response, Iran's Islamic Revolutionary Guard Corps said on Wednesday it had struck US military targets in the region, including in Bahrain, Kuwait and Jordan.
Reuters