The Tusken Raiders reaction states:

" Reaction: After this unit resolves a strike, return it to your hand. "

The Sub-Zero Defenses constant effect states:

" Destroy the first enemy unit to strike against a friendly Hoth objective each turn, after its strike resolves. "

The issue I have is that both of these card abilities occur after a unit strikes. Does section 2.9 of the FaQ cover this situation? Or, do one of the two (constant effects or reactions) occur "faster" than the other

(2.9) Simultaneous Effects Conflict

If the resolution of two or more simultaneous effects would conflict with one another, the active player determines the order in which the effects resolve.

The response from Nate French when previously asked this was:

"Subzero Defenses happens automatically as soon as the strike resolves, before any opportunity to trigger the Tusken Raider reaction occurs."

Check out the "official rule clarifications" thread over at cardgamedb for all the designer clarifications to date.