Why did littlefinger have Jon Arryn killed?

Related questions

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3. How many sons did rhaegar have?
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5. Is Jon Snow Eddard Stark's son?
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Tags

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2. #littlefinger
3. #dagger
4. #arryn
5. #tyrion
6. #valyrian
7. #which
8. #catspaw
9. #murder
10. #attempted
11. #belonged
12. #conspired
13. #assassination
14. #giving
15. #poison
16. #baelish
17. #steel
18. #assassin