Would NATO Membership for Ukraine Undermine Article 5 Itself?

In 2025, Jennifer Kavanaugh and Christopher McCallion wrote, “Armed Neutrality for Ukraine Is NATO’s Least Poor Option,” where they made the case for armed neutrality over full NATO membership as the wiser course for both Ukraine and NATO. A year later, we asked them to revisit their arguments. Image: MidjourneyIn your 2025 article, you argued that NATO membership and binding U.S. or European security guarantees for Ukraine were effectively unworkable, and that armed neutrality was the option best suited to protecting both Ukraine’s security and NATO’s credibility. As the debate has evolved to include talk of “Article 5-like” assurances short of membership, has the trajectory moved toward or away from the armed neutrality outcome you described?It is true that “Article 5-like” assurances have been floated, but it’s unclear what this means and whether these proposals will amount to anything. First, NATO’s Article 5 commitment is unique. It is not simply about the treaty language, but also institutional cooperation and integration. A commitment to Ukraine outside of NATO would not have this weight, and would be very much unlike Article 5 as a result.Second, the way the Trump administration has described hypothetical promises to Ukraine (to the extent it has discussed this issue at all) suggests that the commitment would come from Europe’s Coalition of the Willing, possibly with U.S. logistical support. Since the Coalition of the Willing itself is a loose concept that currently has no clear mandate or allocated forces, it is uncertain what, if anything, is being offered to Ukraine. President Donald Trump has also wavered on whether the United States would commit to providing a backstop of any kind.More importantly, it has been months since there has been any mention of these assurances, in part because even before negotiations stalled, no one seemed satisfied with them. They were