Today may be the first day of summer in the Northern Hemisphere, but winter has come to Westeros in the newest Game of Thrones season 7 trailer. And, with winter, the brutal sting of war.

We’ve long known that winter–literally and metaphorically–has been coming to Jon Snow, Sansa Stark, Daenerys Targaryen, and the rest of the inhabitants of the Game of Thrones universe, but now that winter is now a reality. As Jon stresses in a voiceover throughout the trailer–possibly to Daenerys?–and Sansa says toward the footage’s end, unity is the only thing that will give them a chance to stave off the real threat of the White Walkers.

We’ll see if anyone heeds their warnings when Game of Thrones season 7 premieres July 16 on HBO.

Related: War Is Brewing in New Game of Thrones Season 7 Trailer