The U.S. is expressing doubt about Iran's claim it safely returned a monkey from space.

State Department spokeswoman Victoria Nuland says it's questionable whether the monkey survived - or if the flight happened at all.

She says the simian space traveler whom Iran showed off was missing a wart it had before the purported flight.

Tehran blames the confusion on Iranian media for using a photo of a backup monkey. It says the monkey orbited and returned safely, and President Mahmoud Ahmadinejad added Monday he'd consider being Iran's first astronaut in space.

Nuland described Ahmadinejad's proclamation as an "interesting choice."

Earlier Monday, Sen. John McCain joked about Ahmadinejad in a tweet: "Wasn't he just there last week?" He then linked to a story about the space-orbiting monkey.