Washington DC - President Donald Trump said Thursday it would be a "waste of time" to send ground troops into Iran as the US had already eliminated most of the country's defenses.

"It's a waste of time. They've lost everything. They've lost their navy. They've lost everything they can lose," he told NBC by telephone, adding that Foreign Minister Abbas Araghchi's earlier remark that Iran was ready for a US or Israeli ground invasion was a "wasted comment."

In separate comments made during a White House visit by MLS Cup champions Inter Miami, he also claimed that 60% of Iran's missiles and 64% of its launchers had been taken out.

"Their anti aircraft weapons are gone. So they have no air force. They have no air defence. All of their airplanes are gone," Trump said. "As soon as they set off a missile, within four minutes, the launcher gets hit."

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The 79-year-old repeated his intention to remove Iran's entire leadership structure, after which the US would "go in and clean out everything."

"We don't want someone who would rebuild over a 10-year period," he told NBC.

Trump earlier told Axios he would "have to be involved" in the appointment of Iran's next leader after US-Israeli strikes killed Ayatollah Ali Khamenei and dismissed Khamenei's son as a suitable candidate.