Trump insists Iran nuclear programme set back 'decades'

President Donald Trump insisted Wednesday that US strikes led to the "total obliteration" of Iran's nuclear capabilities and set the country's atomic programme back "decades", while Israel said it was still early to fully assess the damage.

Trump said that the damage to Iranian nuclear sites from American missile strikes over the weekend was severe, even as he acknowledged that the available intelligence on the matter was inconclusive.

His comments followed reports by Reuters and other media outlets on Tuesday revealing that the US Defence Intelligence Agency had assessed that the strikes had set back Iran's nuclear program by just a few months, despite administration officials saying the program had been obliterated.

"The intelligence was ... very inconclusive," Trump told reporters while meeting with NATO Secretary General Mark Rutte ahead of a summit in The Hague.

"The intelligence says, 'We don't know, it could have been very severe.' That's what the intelligence says. So I guess that's correct, but I think we can take the 'we don't know'. It was very severe. It was obliteration," Trump added.

Later, during the same round of comments, Trump argued that Iran's nuclear deal had been set back "basically decades, because I don't think they'll ever do it again".

The president also said on Wednesday Israel and Iran are tired but the conflict between the two countries could start again.

"I dealt with both and they're both tired, exhausted... and can it start again? I guess someday, it can. It could maybe start soon," Trump told reporters.

Asked if the United States would strike again if Iran rebuilt its nuclear enrichment programme, Trump said: "Sure."

Over a 12-day conflict, Israel pounded Iranian nuclear and military sites while Iran launched waves of missiles at its foe during their deadliest-ever confrontation.

The United States joined the fray in support of its ally, hitting two nuclear facilities with massive bunker-buster bombs over the weekend, while a guided missile from a submarine struck a third.

But leaked US intelligence cast doubt on the damage caused by American strikes, saying they had set back Tehran's nuclear programme by just a few months.

"They're not going to be building bombs for a long time," said Trump, adding that the strikes had set back the programme by "decades" and that the Iran-Israel ceasefire that he declared was going "very well".

Earlier, Israel's military said it was "still early" to assess the damage caused to Iran's nuclear programme.

"I believe we have delivered a significant hit to the nuclear programme, and I can also say that we have delayed it by several years," said Israeli military spokesman Brigadier General Effie Defrin.

The head of Israel's military, Eyal Zamir, on Tuesday said Israel and the United States had set back Iran's nuclear programme "by years".

But US media on Tuesday cited people familiar with the Defence Intelligence Agency intelligence report as saying the American strikes did not fully eliminate Iran's centrifuges or enriched uranium stockpiles.

The strikes sealed off entrances to some facilities without destroying underground buildings, according to the report.

Israel had said its bombing campaign, which began on 13 June, was aimed at preventing Iran from acquiring a nuclear weapon, an ambition Tehran has consistently denied.

Israeli Prime Minister Benjamin Netanyahu, in an address to the nation after the ceasefire, announced that "we have thwarted Iran's nuclear project".

"And if anyone in Iran tries to rebuild it, we will act with the same determination, with the same intensity, to foil any attempt," he said.