As the US weighs joining Israel’s assault on Iran, questions are mounting over whether such an intervention could trigger regime change in Tehran – an outcome that risks splintering the country and sending shockwaves across the region.

Iran’s supreme leader, Ayatollah Ali Khamenei, who crushed internal threats repeatedly during more than three decades in power, now faces his greatest challenge yet. His archenemy, Israel, has secured free rein over Iran’s skies and is decimating the country’s military leadership and nuclear program with its punishing air campaign.

Israel has said it does not target Iranian civilians, but hundreds have died in the violence, among them a poet and her family, an equestrian and a graphic designer.

No nuclear weapon has been deployed in war since the U.S. dropped atomic bombs on Hiroshima and Nagasaki in Japan in 1945, and any use of such weapons against an Iranian facility would be extremely controversial in the U.S. and worldwide.

In a statement on Friday, when the attacks were launched, the Israel Defence Forces said they were revealing for the first time Iran's secret and accelerating plan for the development of a nuclear weapon that could threaten Israel.

President Trump sees a “substantial chance of negotiations” and will decide within two weeks whether the U.S. gets involved in the Israel-Iran conflict, says White House Press Secretary Karoline Leavitt.

UN Secretary-General Antonio Guterres warned on Friday that expansion of the Israel-Iran conflict could "ignite a fire no one can control" and called on both sides and potential parties to the conflict to "give peace a chance.

Iran’s supreme leader Ayatollah Ali Khamenei, US President Donald Trump and Israeli Prime Minister Benjamin Netanyahu — stand at the centre of the unfolding war between Israel and Iran. Each has wielded ideological conviction,