Oil prices rose in Asian trade Monday amid growing doubts that the Strait of Hormuz can reopen soon, bolstering concerns over supply disruptions. A top Iranian official made tough demands for the strait’s reopening, while the UAE said Iran launched a missile attack on one of its ships. Both developments threaten to derail a potential deal to reopen the waterway through which one-fifth of the world’s oil is transported. Tehran’s demands include U.S. withdrawal of forces, end of sanctions, and freeing of frozen assets.

Front-month West Texas Intermediate crude oil futures rose 0.1% to $78.29 a barrel and front-month Brent crude oil futures gained 0.3% to $83.80 a barrel. The U.S. dollar found modest support, but uncertainty around the strait keeps risk sentiment cautious, said Samara Hammoud, currency strategist at Commonwealth Bank of Australia.

“Tensions remain high in the Middle East,” ANZ Research analysts said, noting that Abu Dhabi National Oil Co. reported three of its tankers were attacked while transiting the Strait of Hormuz last week.