President Donald Trump and some administration officials have suggested there has been regime change in Iran — a development that would fulfill one of the United States' key war aims.But experts have cast doubt on that assertion, and believe Trump is trying to redefine it in order to the clear the way for the US' exit from its war on Iran — which has spiralled into a regional conflict following the US-Israeli led strikes in late February.It also appears to be at odds with the position of some of the US' allies, including Australia The US has achieved a change in the regime by killing the former supreme leader and other officials, but the regime itself is still intact, clearly," Parmeter told SBS News.Associate professor of international relations at the University of NSW, Jessica Genauer, said the US "definitely" had not achieved regime change in Iran."Whilst a top strata of political and security leaders have been killed, the infrastructure of the regime and the instruments of the regime have remained very much intact," she told SBS News.Genauer said the apparent motivations behind Trump's claims that the regime had been toppled were two-fold