He may be a little young but the Alex Rider books are excellent for spies. The later ones may be too violent for him, but the first is probably okay if you read it to/with him.
If you want him to love reading, then do something like ask him to read the first paragraph and then read the rest of the chapter-or not even that. Let him enjoy the story, and if what it takes is for you to read him some books then go ahead.
I used to do page and page about for a while with ds, then I realised that actually if I read the chapter, he used to often sneak to read another one when he was enjoying it. Win for me!
Depending on his interest/concentration levels some of these are spy/adventure.
Enid Blyton: Adventurous Four have 2/3 adventures which are WWII spy types and relatively easy to read. They're not explicitly WWII, just a mention of "The crooked cross-the enemy of half the world" if I remember rightly.
The Adventure series are also spy type, but for older readers. Some Famous Fives are also spy (#2, #4, #6, #11, #14, #15, #16, #21 from memory), which are harder than Adventurous Four, but easier than Adventure series.
Ds loved the Lone Pine Series. The first (Mystery at Witchend) is a WWII spy story (the American title is Spy in the Hills). Again it's a bit harder, so one to read to him rather than him read, but ds was totally obsessed until we finished the series!