Oil rose as tensions remained high over shipping disruptions in the Red Sea due to a spate of Houthi attacks against vessels in the vital waterway, and after US military strikes in Iraq.

Global benchmark Brent climbed above $80 a barrel after rallying by more than 3% last week, its biggest weekly advance since October. US marker West Texas Intermediate advanced to $75.

The UK navy on Tuesday reported an explosion and missiles seen 4 nautical miles from a vessel off the coast of Yemen, hours after blasts were reported near another ship. In both cases, the ships and their crew were unharmed.

The incidents are the latest in a string of attacks by Iranian-backed Houthi rebels based in Yemen. Despite container giant A.P. Moller-Maersk A/S stating Sunday that it’s preparing to resume using the Red Sea under the protectiopn of the new multinational maritime task force, many other shippers continue to shun the route through the Suez Canal in favor of safer but longer voyages, delaying the delivery of oil cargoes.

The US strikes in Iraq on Christmas Day targeted what it said is an Iranian-based terrorist group blamed for attacks on American personnel, including one Monday which left three people injured. The move highlights the risk that the Israel-Hamas war could widen into a broader regional conflagration.

“Energy supply chains will face yet another round of upheaval” as the Red Sea attacks produce knock-on effects, according to analysts at S&P Global Market Intelligence. “Alternative routings are compromised either practically or economically,” with transits via the Cape of Good Hope adding at least 10 days to journey times.

Crude’s recent gains helped to pare a quarterly decline, as oil remains on course for a loss of about 8% this year. Traders are concerned that despite pledges of further output cuts from the Organization of Petroleum Exporting Countries and its allies, global crude supply may run ahead of demand next year. Angola quit the producer group on Friday amid disagreements over quotas, but remaining members were quick to reaffirm the cartel’s unity.

Timespreads have strengthened over recent sessions. Among them, Brent’s prompt spread — the difference between its two nearest contracts — has swung to 31 cents a barrel in backwardation, a bullish near-term pricing pattern, versus 16 cents a barrel in the opposite contango structure a week ago.

The week between the Christmas and New Year holidays is likely to see lackluster liquidity, with combined aggregate open interest across the main oil contracts tracking lower since about the middle of this month. Oil’s implied volatility has also declined over recent weeks. (Bloomberg)