because Sylvanas think, the blood of azeroth belongs to the horde
Here the Quotes.
.We established a makeshift base in Silithus. Check in with our operatives there--and keep your eyes open for Horde aggression
Master Mathais Shaw
King AnduinThe Horde will stop at nothing to claim the lifeblood of Azeroth. I fear that after the war against the Legion, our ranks are too depleted to stave off their aggression.
King AnduinWe all know the Alliance incurred heavy losses in the war against the Legion. And even now, the world bleeds in the aftermath of Sargeras's final strike.
Meanwhile, the Horde musters its forces and arms for war. Their aggression must not go unanswered.
NathanosGallywix has operations underway in Silithus. Get there at once. And if you see any Alliance skulking about, make quick work of them.
SylvanasWe will bring the Alliance to its knees
.The lifeblood of Azeroth belongs to the Horde
Sylvanas
http://www.wowhead.com/news=277419/d...7-3-5-spoilers