U.S. President Donald Trump is ready to "unleash hell" if Iran does not accept a deal to end the nearly four-week Middle East war, the White House warned Wednesday, but a defiant Tehran said it did not intend to negotiate.

The ramped-up rhetoric dashed hopes of any imminent de-escalation as violence on the ground showed no sign of abating, with Iran, Israel, Lebanon, Bahrain, Kuwait, Jordan and Saudi Arabia all coming under fire.