Complex sentence: On Oct.22,2015, an Anonymous-associated Twitter account announced that the hacking collective had accessed a Klan-associated Twitter account and promised that they would out about 1,000 Klan members by name.
Split into simpler sentences: On Oct.22,2015, an Anonymous-associated Twitter account announced that the hacking collective had accessed a Klan-associated Twitter account. Through that, they promised, Anonymous would be able to out about 1,000 Klan members by name.