As Nour Malas and Joe Parkinson, writing for The Wall Street Journal, put it in a larger piece,
They [Western officials, including especially US officials] now face the choice of launching a major armament program to Kurdish forces, and risk accelerating Iraq’s dismemberment, or offering smaller supplies but failing to turn the Peshmerga into the definitive proxy force against the Islamic State.
Of course, the choice is not limited to these options, nor are these options accurate reflections of reality. An obvious third choice is arming, and supporting with other means, the Peshmerga so that they can do far more than just be someone else’s proxy, but instead guarantee the Kurds’ survival as a society and a polity against ISIS’ attempts to crush, if not exterminate, them—even to crush ISIS instead.
Nor is “launching a major armament program” a serious risk to Iraqi political unity. That threat comes from an Iraqi government that has no respect—no use for—either of the other two major groupings in Iraq: the Kurds, surely, and the Sunnis as well. Arming the Kurds, far from threatening the Iraqi polity, would facilitate the survival and the effectivity of the Kurds, and give them the wherewithal to force the Iraqi government to take them seriously.
On the other hand, not supporting the Kurds adequately, including arming them with serious weaponry and giving them serious air support, guarantees their fall, which in turn guarantees Iraq’s fall to the terrorists.
Which renders irrelevant any discussion of an alleged threat from the Kurds to Iraqi unity.