Tehran has yet to give any clear indication of how it plans to respond to the U.S. attack, saying that it reserved all options to defend itself.

The Islamic republic has also warned of "everlasting consequences" and stepped up its aerial bombardments of Israel, which kicked off the violence 11 days ago with its own surprise strikes on Iranian nuclear infrastructure.

Iran has called Trump a "gambler" and seemed to hint that the weekend strikes have expanded the range of legitimate targets for its military. Trump, meanwhile, raised the question of regime change in Iran in a social media post on Sunday.

Media reports in Iran have suggested that the country is mulling blocking the Strait of Hormuz, a key artery for global oil and gas supplies being sent around the world from Middle East.

Other reports have said that Iran may target one of several U.S. military bases located throughout the region.

Some analysts have argued that, for financial markets, although tensions in the Middle East have now intensified, the strikes have removed at least one shroud of uncertainty around whether Trump would move to strike Iran.

"With the overhang of uncertainty lifted somewhat, the weekend events could wind up being a net positive," analysts at Vital Knowledge said in a note to clients. Still, they flagged that, "once geopolitics fade from the headlines," investors will still be facing "headwinds" from longstanding issues like tariffs and fiscal policy.