US stock futures declined on Monday following the United States' airstrikes on three Iranian nuclear sites over the weekend. This unexpected development has heightened oil prices and ignited fears of an expanded conflict in the Middle East. President Donald Trump had suggested on Friday that a decision on a potential strike would come "within the next two weeks," creating anticipation for possible diplomatic negotiations. However, after the strikes, Trump declared on Saturday, "there will be either peace, or there will be tragedy for Iran far greater than we have witnessed over the last eight days." The markets are now on edge, anticipating potential retaliation from Tehran, which could include attacks on US personnel in the region or disruptions of global oil shipments through the Strait of Hormuz. Last week, major stock indexes showed little movement, as investors proceeded with caution amid rising geopolitical tensions and increasing economic uncertainties.