As Iranians move closer to appointing their next Supreme Leader, US President Donald Trump said in an interview with ABC News on Sunday that a new leader "won't last long" if Iranians don't get his approval first.

"He'll have to get approval from us. If he doesn't get approval from us, he won't last long. We want to make sure we don't have to come back to this every 10 years when you don't have a president like me who's not going to do it," Trump said.

"I don't want people to have to go back five years from now and do the same thing again or, even worse, let them get nuclear weapons," he added.

When asked whether he would approve someone with ties to the old regime, Trump replied: "I would agree, to pick a good leader, I would, yes, I would agree. There are plenty of people that could work."

Apparently offering yet another justification for the war, Trump claimed Iran was planning to take over the entire Middle East and suggested he stopped them from doing so. "They're paper tigers. A week ago they weren't paper tigers, I'll tell you. And they were going to attack. Their plan was to attack the entire Middle East, take over the entire Middle East," the US president said.

He also did not rule out sending special forces to seize Iran's enriched uranium: "Everything is on the table. Everything."