Oil prices advanced on Tuesday, with Brent hovering around a five-month high as traders priced in a geopolitical risk premium from Houthi attacks on Saudi infrastructure and reports of vessel attacks in the Gulf.
Brent crude futures climbed 55 cents, or 0.50%, to $110.10 a barrel by 0319 GMT, after rising as high as $110.70 a barrel in the previous session to their highest since May 20.
The US West Texas Intermediate crude (WTI) contract for November delivery, set to expire on Tuesday, was up 0.24% to $103.91. The more-active December contract rose 39 cents, or 0.40%, to $98.93.
"Oil prices remain well-supported ... This suggests the market is pricing in a significant risk premium, given the situation's volatility," ING analysts said in a note on Tuesday.
"However, if flows continue uninhibited despite the geopolitical environment, the risk premium would likely erode slowly. Clearly, there are no signs of this yet."
At least 18 vessels were reportedly attacked over two weeks, which keeps the risk premium intact, ship-tracker Kpler said in a note on Monday.
On Monday, a Houthi attack on a training camp for government security forces in Yemen's Shabwa province killed 58 people with more than 200 injured.
The renewed attacks heightened fears about regional stability and underscored continuing risks to energy supply from the region, keeping oil prices above $100 a barrel.
In the US, crude oil stockpiles were expected to have fallen last week along with product inventories, a preliminary Reuters poll showed on Monday.
Friday's executive order by President Donald Trump waived key Russia-related US sanctions and tariffs, including goods duties and penalties for purchases of its energy.
However, Trump said on Saturday he had yet to announce a final decision on the matter, while Secretary of State Marco Rubio said officials wanted more time to evaluate the situation.
Russia's crude oil production increased by 65,000 barrels per day in September to 8.43 million bpd, but remained about 870,000 bpd below that of a year ago, the International Energy Agency said last week.
"While the prospect of additional Russian diesel supply offers some theoretical relief, traders appear far more focused on the ongoing risk of further damage to energy infrastructure across the Gulf region," said Tim Waterer, KCM Trade chief analyst.