Oil briefly jumped above $100 a barrel on Wednesday before pulling back below the threshold, as escalating fighting in the Middle East raised fears of further supply disruptions.
Early in European trading, Brent crude, the global benchmark, reached $100.07, before pulling back to around $99.90 as of 4:30 a.m. ET. The move above $100 was the first since July 24.
Brent has climbed about 25% since early August as hopes for a lasting end to the six-month US-Iran conflict have faded. American forces attacked Iranian tankers after Tehran tried to strike a US Navy warship with ballistic missiles, the US military said on Wednesday.
Attacks by Iran-backed Houthi militants this week also set Saudi energy facilities on fire, adding to concerns about oil shipments through the Red Sea and the Strait of Hormuz.
This is a developing story.