Why is an Undersecretary of Defense summoning an ambassador of any kind, much less [View all]

the ambassador to the Holy See?

This question goes to the story making the rounds that Undersecretary of Defense "for Policy Elbridge Colby summoned Cardinal Christophe Pierre — Pope Leo XIV’s then-ambassador to the United States" to the Pentagon, of all places, for a meeting.

Most of the responses to this have quite rightly taken Colby and other Pentagon officials to task for the content of the meeting, threatening the Vatican and invoking the Avignon Papacy and other completely bonkers breaches of basic diplomatic behavior.

But I'm interested in the breach of form as well. Under what auspices can an Undersecretary of Defense summon an ambassador? That's the State Department's job. Was he brought there under the guise of discussing chaplain related issues? I mean, seriously, what the fuck? In what theory of government does the Department of Defense request foreign policy meetings with sitting ambassadors?

The DU story: https://democraticunderground.com/?com=view_post&forum=1002&pid=21158846