"The risk of an invasion is less than most people believe," US foreign policy expert Michael O'Hanlon tells AFP, amid warnings that Russia may be preparing to invade Ukraine. "This time, Putin is giving us weeks of notice. So maybe he's got something else in mind," he says, adding that he believes the Russian president is "trying to intimidate Ukraine, as well as all of us, into not bringing Ukraine into NATO." IMAGES AND SOUNDBITES