Doctor Who Series 10: 10 Things We Learned From The New Trailer
3. UNIT, Is That You?
After disappearing for a while in Matt Smith's era, UNIT has been a major presence over the last few years, particularly with Kate Stewart and Osgood as its two main officers. It wouldn't be a surprise if the alien-busting taskforce turned up again in Series 10, then.
In one shot in the trailer, the Doctor, Bill and Nardole are surrounded by soldiers in some sort of cordoned-off area. The squaddies are seen wearing caps emblazoned with the letters 'UN'. We can't see the rest of it, but these guys could be working for UNIT.
However, they aren't wearing the usual UNIT garb, so these could be soldiers working for the actual UN AKA the United Nations. Which would be a bit weird, but who knows?