Sunday on ABC’s “This Week,” Sen. Chris Murphy (D-CT) questioned as to whether President Donald Trump would “actually stand up for NATO’s Article 5.”

The treaty organization’s Article 5 calls for the collective defense, meaning an attack against one ally is considered an attack against all.

Partial transcript as follows:

KARL: You—you and other Democrats have also been tough on his performance in NATO for being, you know, so—so tough on our allies, particularly Germany. But, as we heard directly from the secretary general of NATO, actually giving him credit for pushing NATO members to give more—to put up more in terms of their defense.

MURPHY: So I think—

KARL: This is an important issue, isn’t it?

MURPHY: Well it is an important issue, but let’s remember the percentage of your budget dedicated to defense is not the sum total of your participation in the alliance. And so what I believe—

KARL: But our allies can pull more of their weight here, can’t they? Or they should?

MURPHY: They—they certainly can, but so can we. Let’s think about the refugee crisis for a moment. If you talk about the burden of dealing with the outflow of refugees from the Middle East, the United States is not picking up our share of the burden, it’s the Europeans that are doing it almost alone.

And so there are grievances on both sides of this alliance. President Trump made a decision that he was going to try to undermine NATO, undermine the E.U. He has used the two percent number as a means by which to do it.

But let’s be clear, NATO today is arguably functionally obsolete in the sense that—do you really believe that if the Europeans were attacked in the Baltic States for instance by Russia, that President Trump would leap to their defense?

Do you believe today that if the United States—

KARL: Article 5 says we would.

MURPHY: Well it’s always going to be a political decision as to whether you actually enforce Article 5, and I think that there is a very important question today as to whether President Trump would actually stand up for Article 5, and I think NATO is just trying to survive the next two and a half years by saying these nice things about the state of the alliance so that it’s still there when Trump’s gone.

KARL: All right, Senator Murphy, thank you for joining us—