The U.S.-Israel war on Iran that began Feb. 28 and "toppled the regime" in Tehran but brought change "for the worse," according to a Wall Street Journal report Wednesday.

The report claimed that a billboard in Tehran displaying the image of newly selected Supreme Leader Mojtaba Khamenei represented the "worst nightmare" of opponents of the incumbent government.

This will be "a militarized Iran ruled by a younger, hard-line leader where the Revolutionary Guard plays an even more dominant role."

The U.S. and Israel initiated the war believing that eliminating senior Iranian figures – beginning with Mojtaba's father, Ali Khamenei – might pave the way for regime change or at least bring forward leaders more aligned with their interests.

However, rather than achieving that outcome, the resulting power vacuum is being occupied by "radical new leaders" who appear largely unwilling to pursue political compromise, either domestically or internationally, the report said.

"The war changed the regime – and not in a good way," said Danny Citrinowicz, who formerly headed the Iran desk for Israeli military intelligence. "We created a reality that is worse than what Iranians were facing before the war."

Iran's hard-liners now dominate the country's political and military leadership, energized by a war that many of them believe presages the return of a "Shiite Muslim messiah," the report said.