Complex sentence: Meanwhile, Jake faces a dilemma: while the fastest way to be done with the mission would be to kill Oswald well before the Kennedy assassination, Jake is hesitant to do so since Oswald might not have acted alone.
Split into simpler sentences: Meanwhile, Jake faces a moral dilemma: the fastest way to be done with the mission would be to kill Oswald well before the Kennedy assassination. Jake, however, is hesitant to do so because of the possibility that Oswald might not have acted alone.