Oil held a gain as traders weighed the outlook for a reopening of the Strait of Hormuz after a cargo ship was attacked in the waterway.West Texas Intermediate traded above US$71 a barrel after climbing more than 2 per cent on June 25, the first increase in five days. Brent rebounded to close near US$75 after earlier erasing all of its wartime gains in the session. The vessel was struck by an unknown projectile, while it was sailing south-east of Oman.Ships had been openly transiting the crucial waterway following early progress towards a lasting agreement to end the war, adding millions of barrels to the global market. Further discussions between the US and Iran are likely to be protracted on issues including nuclear policy, but oil futures have rapidly declined recently and are still on track for a third weekly loss.The Wall Street Journal reported the vessel was struck in an attack by Iran, although a White House official said it was too soon to say who carried out the attack. The official, who spoke on condition of anonymity, said the US was looking into which party was responsible for the strike.The incident came as several commercial ships turned around while attempting to transit the strait, raising fresh doubts over how quickly flows can normalize. The International Maritime Organization, the United Nations’ global shipping regulator, said it was pausing its evacuation operations in the strait.Earlier this week, Persian Gulf oil was streaming out of the waterway at the fastest pace since the war began. Goldman Sachs Group Inc. said it sees Gulf exports now running at almost two-thirds of normal levels, while the pace of visible global inventory declines has slowed. BLOOMBERG