There were no signs of letup in the U.S.-Israel war on Iran Monday after Tehran named Mojtaba Khamenei to replace his slain father ​as supreme leader.

The appointment signaled that hardliners remain firmly in charge and appeared to close off any path to a swift end to the war amid U.S. threats.

The prospect that the disruption to global energy supplies – already one of the ⁠most severe in history – could last longer than previously expected sent oil prices ⁠surging in record leaps and global stock markets into a nosedive.

Khamenei, 56, a Shiite cleric with a power base among the security forces and their vast business empire, has been declared unacceptable by U.S. President Donald Trump, who has demanded Iran's unconditional surrender.

Iranian state media showed large crowds in the streets ​of several cities showing support for the new leader, carrying Iranian flags and portraits of his father Ali Khamenei, killed by ​strikes ⁠on the war's first day.