Richard Fontaine makes a reasonable case that foreign policy debate has always been politicized and partisan, but then he says this:

The open nature of the American political system permits genuinely new ideas to enter calcified foreign policy debates, which may over time improve the quality of the country’s policymaking.

I suppose it depends on what one means by “genuinely new ideas,” but this doesn’t resemble foreign policy debate as I have known it during my lifetime. The range of ideas in conventional foreign policy debate is usually very limited, and there are hardly any “genuinely new ideas” introduced into the debate. Actual policy-making moves between two poles within a very narrow bipartisan consensus. Even when there are some real differences between party leaders on a particular issue, they are inevitably very small differences, and for the most part differences have to be manufactured and then grossly exaggerated for political purposes. Consider the example of missile defense in Europe. There doesn’t appear to be any major substantive disagreement between party leaders on this issue, and there seems to be bipartisan support for European missile defense. This underscores just how politicized foreign policy can be. Partisan opponents will politicize a foreign policy issue even when, or perhaps especially when, there are no real policy differences at stake. Indeed, it is easier to politicize a foreign policy issue when both sides realize that there is no substantive disagreement involved.