Star Wars Episode 9 Trailer Breakdown: 16 Things You Need To See
12. Kylo Seeing Red (On Endor?)
Speaking of Kylo Ren, there's at least no mistaking that this is him, and he's in the midst of an attack on...
Could that be Endor? Based upon what we see later in the trailer, there's a great chance that the Saga is returning to Endor in Episode IX, and that means a good chance of characters converging there. Those trees would definitely fit with the general look of the planet, and given how connected it is to the fall of Vader, it's absolutely the kind of place Kylo would be interested in. There's also a question of who he's fighting: it could just be a Resistance fighter, and how quickly it passes makes it difficult to gauge, but it could even be a Knight of Ren, who will be back in this film. At just a glance, it does fit with concept art for the group.
On the other hand, if this IS Endor, then there's also the chance of it being a flashback, since he'd have had to go there in order to retreive Darth Vader's mask (which is confirmed to return in Episode IX as well).