The founder of CNN also defended the right of Iran to have nuclear weapons and the effectiveness of the United Nations and, in a jocular mood, advocated banning men from elective office worldwide.
Addressing a Alternately combative and humourous, Turner spoke nine years after his pledge to donate $1 billion to the United Nations over 10 years and on the same day US President George W. Bush addressed the UN General Assembly nearby.
He said the US invasion of Iraq has caused "incalculable damage" that will still take 20 years to overcome "if we just act reasonably intelligently."
"It will go down in history, it is already being seen in history, as one of the dumbest moves that was ever made by anybody.
A couple of others that come to mind were the Japanese bombing of Pearl Harbour and the German invasion of Russia," Turner told a corporate forum.
"It literally broke my heart. You don't start wars just because you don't like somebody ... I wouldn't even start a war with Rupert Murdoch," Turner said, referring to his onetime cable network rival.
Often contrarian, Turner called it a "joke" that Bush demanded that Iran abandon any ambitions for nuclear weapons while at the same time hoping to ban all such bombs.
"They're a sovereign state," Turner said of Iran.
"We have 28,000. Why can't they have 10? We don't say anything about Israel -- they've got 100 of them approximately -- or India or Pakistan or Russia.
“And really, nobody should have them … they aren't usable by any sane person."