Oil prices fell on Monday as US President Donald Trump’s decision to waive sanctions and tariffs on Russia raised the prospect of additional fuel supplies entering the market. However, continuing security threats in the Middle East and uncertainty over US-Iran negotiations kept the outlook for crude volatile.Brent crude declined $1.56, or 1.42%, to $108.3, while West Texas Intermediate (WTI) crude was down 0.25, or 0.25%, at $101.2 a barrel.The previous week, US President Donald Trump had signed an executive order granting a waiver on key sanctions and tariffs imposed under the law known as the Graham Act. The legislation was signed last month after lawmakers urged the president to put pressure on Moscow over its war in Ukraine.Secretary of state Marco Rubio said Trump would use up to 60 days to evaluate the economic consequences of the waiver.The move came after Trump reached an agreement with Russian President Vladimir Putin to export diesel to the US. Ukrainian President Volodymyr Zelenskiy criticised the US actions, saying they would hurt Ukraine.Brent crude had climbed to $110 a barrel briefly on Friday, marking its first such level since May, as mounting tensions in the Middle East heightened concerns about the security of shipping routes and the availability of global energy supplies.The pressure on supplies has been compounded by attacks on commercial vessels. Gulf crude flows fell to approximately 8.5 million barrels per day on a seven-day average last week, down from more than 20 million barrels per day in the previous week, according to analytics firm Kpler. In a note issued on Friday, the firm also reported at least 10 confirmed incidents involving commercial vessels during the week.The risk of a wider regional confrontation remained in focus, with Egypt stating that it was prepared to offer Saudi Arabia the support required to protect its security and stability against Yemen’s Iran-allied Houthis.Despite Monday’s decline, crude markets face another week of potential price swings. Supply concerns across West Asia and stalled negotiations between the US and Iran are fuelling fears of further disruptions, while measures aimed at easing shortages are providing some relief, analysts said.Market participants will look to upcoming inventory figures for a clearer picture of supply and demand. The data under scrutiny include weekly crude stock estimates from the American Petroleum Institute (API), inventories at Cushing, total US oil stocks and crude imports.Developments around the Strait of Hormuz will also remain crucial to the market outlook. Any interruption to shipments through the strategic waterway could further restrict global oil supplies, adding to the uncertainty surrounding prices.