Small contingents of soldiers from NATO member nations arrived Wednesday in Greenland, symbolically supporting Denmark’s claim to the territory against Trump administration rhetoric. “From today, there will be an expanded military presence in and around Greenland — in close cooperation with NATO allies,” the Danish Defense Ministry stated.

For weeks, President Donald Trump has been dropping comments about his desire to acquire Greenland for the United States. “Anything less” than U.S. control of Greenland is “unacceptable,” he insisted on social media Wednesday, hours before Danish officials met with Secretary of State Marco Rubio and Vice President J.D. Vance. Last Friday, he claimed he was “going to do something on Greenland, whether they like it or not.”

The declarations have spooked not only Greenlanders and Danes, but the entire NATO alliance. Six other NATO members sent troops to Greenland on Wednesday for two days of exercises. The numbers were small (15 from France, 13 from Germany, one from the Netherlands, two from Norway, two from Finland, and an unspecified number from Sweden). But they sent a major message: any American move against Greenland would not only be an attack on Denmark but on the entire NATO alliance.

Respecting each member’s territorial integrity is a crucial aspect of the NATO alliance. The North Atlantic Treaty of 1949 guarantees each member nation the right to “consult together” whenever “the territorial integrity” of any party is threatened (Article 4). It also defines an armed attack on any party, which “shall be considered an attack against them all” (Article 5), as an attack upon their territory or forces in Europe and North America (Article 6).

As a result, Danish Foreign Minister Lars Løkke Rasmussen warned that any American invasion of Greenland would spell “the end of NATO.”

For his part, President Trump insists that “The United States needs Greenland for the purpose of national security.” In particular, Greenland is an integral part of his planned “Golden Dome” missile defense shield that would cover North America. In general, Trump fears that, if the U.S. does not secure Greenland’s vast territory, “Russia or China will.”

“There’s absolutely no Chinese footprint in Greenland,” responded Rasmussen. “Having said that … there’s always a bit of truth in what he [Trump] is saying. We definitely share the concern that [the] Arctic is not any longer a low-tension region. And, of course, we have to be aware of that. And that’s why we have invested almost $15 billion U.S. dollars last year in capabilities in Greenland.”

“We all belong to NATO. And we think that our way forward should be that we combine forces,” he added. Denmark has emphasized its military cooperation with the U.S., saying that its forces in Greenland provided support to the U.S. military in the capture of a rogue tanker that fled from Venezuela to the coast of Scotland.

Under a 1951 treaty with Denmark, the United States has latitude to install military bases and other defenses on the island. Currently, the U.S. operates a small Air Force base on Greenland’s western coast. But it could expand that base or build new ones if the security situation required it.

Considering all the factors at play, Danish Deputy Prime Minister Troels Lund Poulsen assessed that it is “unlikely that a NATO nation would attack another NATO country.” It may be unlikely, but it is no longer unspeakable, and that downgrade in confidence prompted other NATO powers to send troops to Greenland — just to be sure.