Define "advantage." I think the Iranians have the power to damage or destroy a US aircraft carrier battle group operating in the Persian Gulf. I also think that in any armed conflict, US casualties would be lower than Iranian casualties. But that's not really the point -- the destruction of a carrier battle group (regardless of the cost to Iran) would be a huge psychological defeat for the US. What I think is more likely is that the Iranians could force carrier battle groups to operate so far out in the Arabian Sea, that their ability to operate effectively over Iran would be generally negated.