Politicians and pundits have been using the phrase "boots on the ground" to declare limits in US involvement in the Middle East. But what does that phrase mean, anyway? Why do troops mean war but airstrikes don't? And what does the distinction mean for the public's willingness to engage militarily in the region? Bob talks to Kathy Gilsinan, a senior associate editor at the Atlantic covering covers global affairs, about how this phrase has been used to blur the definition of war in the public consciousness.