Oil prices edged higher on Friday and were heading toward a weekly gain of about 4 percent, as hostilities between the United States and Iran returned to the forefront of concerns for traders and analysts. The renewed focus was spurred by Qatar, Kuwait, Egypt and Bahrain condemning an Iranian attack on two tankers affiliated with the United Arab Emirates as they transited the Strait of Hormuz, the narrow chokepoint between Iran and Oman that normally carries roughly a fifth of the world's traded oil.

As of 0247 GMT, Brent crude, the international benchmark, had risen 1 cent to $87.08 per barrel, while West Texas Intermediate, the U.S. benchmark, was up 6 cents at $81.31 per barrel.

The four Middle Eastern countries declared full solidarity and rejected the Islamic Republic's claim of control over the Hormuz. Strategically, however, and in terms of potential trading influence, Washington's approach to Iran was viewed by some as far more impactful, with the possibility that the country's military regime could ultimately descend into chaos.

On Thursday, the U.S. warned that it could maintain a naval blockade of Iran indefinitely and increase economic pressure on Tehran, as ceasefire talks have stalled.

U.S. Treasury Secretary Scott Bessent told media, "Watch this space for more announcements coming next week because we are going to apply measures like have never been seen in the history of economic isolation of a country."

The escalation prompted dismay among some pundits. Bjarne Schieldrop, analyst at SEB Research, said, "A return to normal flows out of the Strait of Hormuz is now suddenly without any near-term hopes."

In other war-related oil news on Friday, at least four Asia-based refiners have increased purchases of U.S. crude supply this week as an alternative to Middle East crude that may not make the outbound journey through the Hormuz, according to traders. The shift illustrates how supply disruptions at the chokepoint redirect trade flows toward Atlantic Basin barrels, which reach Asia without passing through Hormuz.

The transactions include GS Caltex of South Korea buying 2 million barrels of Mars crude from Shell for delivery in November, at a premium of $13-14 above the Dubai October benchmark. Mars is a medium-sour grade produced in the U.S. Gulf of Mexico, a quality closer to the sour crudes that dominate Middle East supply than lighter grades such as WTI.

Additionally, Cosmo Energy Holdings, one of Japan's biggest refiners, bought Mars supply from Trafigura, while CPC Corp, the state-owned energy company of Taiwan, acquired 2 million barrels of WTI via a tender at a premium of around $8 to $9 per barrel to Dated Brent, the premiums underscoring what buyers are paying for supply that avoids the contested waterway.