Washington (CNN) -- A Friday exchange between Democratic presidential candidate Joe Biden and a Fox News journalist has drawn attention to Biden's shifting accounts of what he advised President Barack Obama about the 2011 raid that killed Osama bin Laden. Fox News journalist Peter Doocy challenged Biden about his criticism of President Donald Trump's decision to order the killing of Iranian military commander Qasem Soleimani. Doocy asked Biden if he would be willing, as commander-in-chief, to thwart an "imminent attack on Americans" by using an airstrike to kill a "terrorist leader." (Trump claimed on Friday, without providing evidence, that Soleimani...