I mean left on the political spectrum, and certainly far more left-wing than mainstream Democrats or "center" left (even in a British or European context). Additionally, I use the term skepticism here similarly to how the term euroskepticism is used to encompass varying degrees of criticism for the European Union (including criticism that involves full withdrawal of all member states), just in this case in regard to NATO. As I said in my initial comment, I'm well aware that many on the left want to see the dissolution of NATO.

I don't think I would describe myself necessarily as pro-NATO, I just don't think its dissolution is reasonable, and I think its actually quite arguable that NATO dissolution would be a net negative. With that in mind, it's not uncommon for people, who are otherwise very far off from one another on the ideological or political spectrum, to agree (or at least agree in policy outcome) on individual issues (especially foreign policy ones). That's the nature of using a relatively one-dimensional spectrum to describe a complex system of beliefs.