"Actually, if you look at Hiroshima, if you look at Nagasaki, you know that ended a war too," Trump said as he wrapped up NATO's summit in The Hague.

"This ended a war in a different way, but it was so devastating."

Trump has ferociously defended his assertion that the US strikes using bunker-busting bombs "obliterated" Iran's underground Fordo nuclear facility.

US media has reported that a classified preliminary US intelligence report concluded that American strikes on Iran had set back Tehran's nuclear programme by just a few months -- rather than destroying it.

"Was it bad? It was really bad," Trump said. "It was obliterated."

In the wake of the strikes on Iran, Trump announced that he had secured a ceasefire between Iran and Israel to halt their 12-day war.

On August 6, 1945, the United States bombed Hiroshima, killing 140,000 in the explosion and by the end of the year from the uranium bomb's effects.

Three days later, a US plane dropped a plutonium bomb on Nagasaki, leaving around 74,000 people dead by the end of the year. Japan surrendered on August 15.