European stocks opened lower on Tuesday, as escalating tensions in the Middle East dampened market risk appetite and posed a potential threat to a four-week ceasefire between the US and Iran. US forces repelled an Iranian attack while escorting two US-flagged ships through the Strait of Hormuz, after reports of an Iranian drone strike on the port of Fujairah in the UAE. Oil prices climbed again, exacerbating concerns about inflation and reinforcing expectations that central banks may need to further tighten monetary policy to curb rising oil prices. In Europe, investors will be watching the latest earnings reports from companies such as AXA, AB InBev, Infineon Technologies, Ferrari, and Ferguson. Meanwhile, HSBC reported first-quarter pre-tax profit of $9.4 billion, below expectations, due to anticipated credit losses and other impairment charges. In pre-market trading, both the Euro Stoxx 50 and Stoxx 600 futures fell by about 0.1%.