There are 3 books in the Terminator series. The newest book is The Future War which came out in 2003.

1
Infiltrator

Book cover of Infiltrator
Return to the blockbuster Terminator universe, with the untold adventures of Sarah and John Connor! Following "Terminator 2: Judgment Day", Sarah and John Connor fled to Paraguay, until one day Sarah spots a Terminator unit in the town square. A great cat-and-mouse game ensues before she realizes he's an actual…
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2
Rising Storm

Rising Storm
The Infiltrator is dead. The Terminators destroyed. But the war is far from over. Severely injured and recuperating in a military hospital, Sarah Connor discovers some shocking information. Meanwhile, John Connor, aided by the former counter-terrorist Dieter von Rossbach, begins a desperate campaign to prepare humanity for the dark times…

3
The Future War

The Future War
Return to the blockbuster Terminator universe, with the untold adventures of Sarah and John Connor! The future war is now. Hiding out in Alaska, Sarah and John Connor, along with ex-counter-terrorist agent Dieter von Rossbach, are playing a waiting game - trying to live their lives, but ever watchful of…