The Washington foreign-policy establishment, working in concert with the Europeans, has been trying for years to “Trump-proof” both endless US aid to Ukraine and endless US dominance of Europe.

The new Trump administration can blow through most of these efforts if it chooses. And it should.

To much fanfare a few months ago, the effort to distribute military aid to Ukraine was moved from the US aegis to the NATO one. This was widely viewed as an effort to “Trump-proof” military aid to Ukraine, but it was never quite clear how it would Trump-proof the aid. The bulk of the military aid that has been instrumental to Ukraine’s survival thus far has come from the United States. A NATO bureaucracy can’t prevent a US president from simply not requesting more aid.

The more interesting angle is the domestic effort to constrain the president. In a thinly veiled effort to hamstring Trump, Senators Tim Kaine and Marco Rubio authored a bill that Congress passed last year prohibiting the use of any funds “to support, directly or indirectly, any decision on the part of any United States Government official to suspend, terminate, denounce, or withdraw the United States from the North Atlantic Treaty” without two-thirds of the Senate approving.

This legal formalist approach is unlikely to constrain a motivated president. Trump wouldn’t have to do a mortgage’s worth of paperwork to distance the United States from being taken advantage of by Europe. He could simply walk to a podium and say, “You know, when you look at Article 5, some people, the worst people, are saying that this means Americans have to protect Europeans forever. I think Article 5 means something different. Something very different, something beautiful, actually. And you know, Article 11, maybe the most beautiful article of all, says the treaty needs to be ‘carried out by the Parties in accordance with their respective constitutional processes.’ So this idea that America would automatically go to war for these European freeloaders… Well, I would never do that.”

In the same speech, he could repeat the pledge he made to David Sacks on the All-In Podcast that he would never send US troops to Ukraine and make clear, as a consequence, that he opposed letting Ukraine join the alliance.

Such a speech would be an enormous blow to NATO. It would make clear Washington’s waning interest in being the cornerstone of European security and call into question what Joe Biden and Kamala Harris called the “sacred” nature of the US commitment. Trump could do this without spending a single congressionally allocated dollar.

Instead, or in addition to a speech making clear his interpretation of Article 5, Trump could just Irish goodbye the alliance. He could do this in any number of ways: removing tens of thousands of troops from Germany, for example, or participating at a lower level—or none at all—in alliance military planning. He could insist that the next Supreme Allied Commander be a European, which none has ever been before. Any of these moves, much less all of them, would come as a massive shock to Europe.

By giving a speech like the one I outline above, or by Irish goodbying the alliance, or by doing both, Trump would dare Congress to invoke its legislation to stop him by taking the question to a judiciary that has been exceedingly deferential to the executive on foreign policy questions. It seems unlikely that the jurisprudence surrounding presidential authority in foreign policy could regulate his speechmaking or his movement of forces overseas.

Washington’s blank check to Ukraine has gone on too long, as has its dominance of European security affairs. Trump has a generational opportunity to renegotiate the division of labor on European security and get American taxpayers and servicemembers a better deal.

If he wants to, Congress and NATO likely cannot stop him.