WASHINGTON (AFP) - US Defence Secretary Robert Gates said Sunday that Iran was more likely to heed sanctions than diplomacy in US efforts to dismantle its nuclear drive. Apparently contradicting President Barack Obama's diplomatic overtures to Iran, Gates said on "Fox News Sunday": "I think frankly from my perspective the opportunity for success is probably more in economic sanctions in both places (Iran and North Korea) than it is in diplomacy." "Diplomacy perhaps if there is enough economic pressure placed on Iran, diplomacy can provide them an open door through which they can walk if they choose to change their policies," the Pentagon chief said. "And so I think the two go hand in hand, but I think what gets them to the table is economic sanctions." On North Korea, Gates said a missile launch by Pyongyang appeared imminent but that the US would not shoot it down. He appeared to contradict Admiral Timothy Keating, head of the US Pacific Command, who had reportedly said the military was ready to shoot down the missile if given the order. "I think if we had a missile that was heading for Hawaii, that looked like it was headed for Hawaii or something like that, we might consider it. I don't think we have any plans to do anything like that at this point," Gates said. Asked if the launch was set to happen, the Pentagon chief said: "I think it probably will." "I would say we're not prepared to do anything about it," he added, following Keating's remark in an interview with ABC News. Gates said the US government believed the launch was "intended as a mask for the development of an intercontinental ballistic missile," but that this type of missile did not have the range to reach Alaska. "I personally would be sceptical that they have the ability right now to do that." Asked if Japan might shoot down the missile, Gates cited media reports to say that "if that missile fails and it looks like it's going to drop debris on Japan, that they might take some action." The Pentagon chief said the missile development was "very troubling" and said six-party talks on disarming North Korea's nuclear programme "really have not made any headway any time recently." "If this is (North Korea leader) Kim Jong-Il's welcoming present to a new (US) president, launching a missile like this and threatening to have a nuclear test, I think it says a lot about the imperviousness of this regime in North Korea to any kind of diplomatic overtures." Meanwhile, the commander of US forces in the Middle East said Iran is still "a couple of years" away from having enough highly enriched uranium to make a nuclear weapon. "The bottom line: we think it's a couple of years away in that regard. It could be more, could be a little bit less," General David Petraeus, the head of the US Central Command, said in interview on CNN. "There are certainly a lot of facts that we don't know about what goes on inside Iran," he added.