The aid is the key card that can be played.

To give money is a dreadful idea as it'll just go missing.
To give very high tech stuff is probably a waste. Upkeep will be tough, and it'll break.
But to give a load of low(er) tech stuff will likely be used in equipping other groups.
If invested in Education, it'd be spun as Western propaganda.
So, I would say the money would be best spent on infrastructure where it goes to the Civilian government (boosting their clout) and helps things in a non-specific way.

I don't see how the nukes can be kept safe easily - but then the fall of the USSR was managed so clearly there are ways.