Ian Douglas 
Deep Time 
Star Carrier: Book Six

The clock is ticking in the struggle for galactic independence Once rebels themselves facing off against the Earth Confederation, the United States of North America is now the dominant force in negotiations with the interstellar Shdaar Collective. But just as the Marines root out the last violent dissenters, an alien ship of unknown origin suddenly flees Earths orbit. Is it mere coincidence . . . or a terrifying omen?President Alexander Koenig watches with great interest as USNA forces chase the runaways down. But upon first contact, its not apparent whereor whenthe crew is headed. For this bizarre species has somehow mastered the power to manipulate time itself. Now Koenig must decide whether hes dealing with angels of astonishing technological prowess . . . or the agents of humanitys destruction.