U.S. markets opened cautiously on Monday as investors monitored escalating tensions in West Asia following American airstrikes on Iranian nuclear facilities over the weekend. At the opening bell, the Dow Jones Industrial Average slipped 28.3 points, or 0.07%, to 42,178.55. The S&P 500 edged up by 1.8 points, or 0.03%, to 5,969.67, while the Nasdaq Composite dipped 20.4 points, or 0.10%, to 19,427.01.

Meanwhile, White House reaffirmed President Donald Trump’s assertion that the strikes had severely damaged Iran’s nuclear infrastructure. Speaking on ABC’s “Good Morning America,” White House Press Secretary Karoline Leavitt said, “We are confident that Iran’s nuclear sites were completely and totally obliterated, as the president stated during his address on Saturday night. Intelligence confirmed that the strikes targeted locations where enriched uranium was being stored.” Leavitt added that the decision to launch the strikes was made only after receiving firm intelligence, and that the administration remains confident in the outcome.

Iran, meanwhile, has vowed to respond, accusing the United States of a direct and unlawful act of aggression. In a brief statement issued Monday morning, General Abdolrahim Mousavi, newly appointed Chief of Staff of Iran’s armed forces, accused the U.S. of breaching Iranian sovereignty by targeting the key nuclear sites at Fordow, Natanz, and Isfahan.

“The United States has clearly and directly entered the war,” Mousavi said, hinting at further consequences.

Iran has already intensified its military campaign against Israel, launching a new round of missile and drone attacks. Ebrahim Zolfaghari, currently acting as spokesperson for Iran’s retaliation efforts, addressed the situation in a televised statement Monday, accusing the U.S. of trying to prop up what he called “a collapsing Zionist regime.” “These attacks will only broaden the scope of legitimate targets for our armed forces and lay the foundation for a wider war in the region,” Zolfaghari warned.