I suspect Obama's Iran deal and Hillary's support for Russian weapons development are parts of a strategy to limit the power of the United States and force US politics to focus on domestic issues, where Democrats believe they are strong and Republicans are weak.
Generally, Republicans are more focused on foreign involvement, and Democrats on domestic involvement. If the Democrats can make foreign involvement much less meaningful, then they force US politics to focus on the Democrats' strengths.
By helping Iran and Russia become militarily powerful nations, they make the stakes for US military involvement overseas much, much higher. In addition, weakening relations with our traditional military allies also limits us. Doing these things will almost certainly lead to a much lower probability of US military action in those regions. This can be used to claim we don't need as much military power and then to reduce our forces, which will further limit our options. (As a bonus, the military is a hotbed of Republican support, so reducing it is always good for Democrats.)
Given our own weakness in the face of powerful foreign forces, they can then, quite reasonably, claim that since we can't do much about what foreign nations do, we should focus on social justice here. Voila! The entire national debate shifts dramatically.
It's just a hunch, though.