New Delhi, Oct. 23 -- The India-US trade agreement is in its "last mile" but "it's never done till it's done", external affairs minister S Jaishankar said on Thursday about efforts by the two countries to find common ground on the deal they have negotiated for more than a year. US secretary of state Marco Rubio and commerce minister Piyush Goyal too have spoken of the two sides moving towards the final stages of the trade deal, he said at a session at the NDTV World Summit. "But.often the last mile or the penultimate miles do pose their challenges. I think the [negotiating] teams are working through them now," Jaishankar said. "If you're asking me to tell you what exactly those challenges are, I'm sorry I won't. That's for the negotiators t...