The US oil benchmark fell to its lowest level since February 2021, with traders weighing renewed signs of optimism surrounding a deal to end the war in Ukraine and mixed economic data from China. West Texas Intermediate settled below $57 a barrel in thin trading ahead of the Christmas and New Year holidays, sliding as stocks wavered. US negotiators offered more substantial security guarantees to Kyiv in a renewed bid to clinch a deal, though the effort still appeared part of a bid to pressure Ukrainian Pr ...