The requirements for the naturalization of the spouse of a US citizen are described here and will usually require him to have been a permanent resident (green card holder) living with you in the US for at least 3 years, and to have spent at least half that period physically present in the US. There are some exceptions to the 3 year requirement that might apply if you were employed overseas by the US military, the US government or certain other US organizations, but even these require the spouse to be a permanent resident at the time of application. I'm also guessing none of these will be useful to your case.
Given this I think the only way for him to use his relationship to you to acquire US citizenship is for you to:
- Sponsor your spouse for US permanent residence (there will be some complexity with this since you yourself don't live there), and
- Move to the US and live there with him for the time it takes for him to become eligible for naturalization.
If you want US citizenship for him so he can eventually move to the US with you, you can't do that but can always apply for a green card for him at a time when you'd like to move. If you want US citizenship for him only, say, because a US passport is a more convenient travel document than the one he has now, this is not something you can do at all.