The nature of the trans-Atlantic alliance has dramatically shifted. Over four generations, the West was built on long-term trust and open-ended collaboration on common interests: containing the Soviets during the Cold War, expanding the liberal order, defeating al Qaeda and the Islamic State, countering Russian aggression, and meeting the China challenge.

Now, that trust is gone, and a partnership based on common interests has been replaced by a flexible transactionalism. The focus is on horse trading and ad-hoc deals, such as the U.S.-EU trade framework agreement and the purchase of U.S. weapons by European NATO members on behalf of Ukraine, which I proposed in these pages long before it came about.

The nature of the trans-Atlantic alliance has dramatically shifted. Over four generations, the West was built on long-term trust and open-ended collaboration on common interests: containing the Soviets during the Cold War, expanding the liberal order, defeating al Qaeda and the Islamic State, countering Russian aggression, and meeting the China challenge.

Now, that trust is gone, and a partnership based on common interests has been replaced by a flexible transactionalism. The focus is on horse trading and ad-hoc deals, such as the U.S.-EU trade framework agreement and the purchase of U.S. weapons by European NATO members on behalf of Ukraine, which I proposed in these pages long before it came about.

Europe buying U.S.-made arms for Ukraine is only second-best after direct American support, but it is better than no U.S. deliveries at all. Similarly, transactionalism is not as effective as partnership, but it is still better than separation. German Chancellor Friedrich Merz expressed Europe’s sober realism when he said, “whether we like it or not, we will remain dependent on the United States of America for some time to come.”

This reliance is particularly stark in security, whether that concerns the defense of Ukraine or of the continent as a whole.

As Merz’s admission suggests, European leaders must face reality and look for mutually beneficial deals if they have any hope of keeping Washington engaged. One opportunity to do just that is the 150 billion euro ($176 billion) Security Action for Europe (SAFE) fund, a new European Union defense fund that currently cannot be accessed by U.S. and other non-EU firms. Opening this fund to U.S. defense companies could—if negotiated smartly—be Europe’s leverage to get Washington to seal the deal on the $90 billion weapons package that it has been negotiating with Ukraine, including long-range Tomahawk missiles and additional Patriot air defense systems that only the United States can provide.

The SAFE program, adopted by the EU in May, provides 150 billion euros in long-maturity loans for arms procurement by member states. The European Commission has so far received requests for a total of 127 billion euros ($148 billion) from 18 members, including France, Italy, Poland, and Spain. Non-EU companies, such as U.S. defense firms, are restricted to receiving a maximum of 35 percent of the costs of each project financed under this scheme.

Countries that have concluded a security and defense partnership with the EU are exempt from this limit, as long as they also sign an additional technical agreement that sets out the terms of their participation in the SAFE program. Six countries, including Japan and South Korea, have already done so. Britain and Canada are expected to conclude the negotiations over the next few weeks, placing them in a more privileged position than the United States.

Senior EU officials recently told me that the EU would be open to the United States also joining but that Washington has not expressed any interest so far. Several U.S. officials suggested to me over the summer that Washington could try to overturn SAFE altogether, but this is highly unrealistic given EU unity over a program that is now well advanced.

The Trump administration should make this deal happen and could do so with little effort: The United States is already committed to European security through NATO and could complete the additional paperwork quickly. This would unleash tens of billions of additional funding for U.S. firms and could be linked to the negotiations with Ukraine over a large-scale U.S. weapons package financed by Ukraine and its European partners.

Not only would giving Washington access to SAFE funds signal Europe’s willingness to deepen trans-Atlantic defense cooperation, but it would also satisfy Washington’s objectives of selling more defense gear to the Europeans and reducing the U.S. trade deficit. For Europe, sustained U.S. interest in its security remains essential, at least in the near term, as the continent belatedly ramps up its own defense production and tries to close various capability and technology gaps.

With investment still lacking, one assessment by the International Institute for Strategic Studies found that Europe’s defense industry will struggle to replace U.S. capabilities for at least another decade. Keeping Washington committed is thus crucial—and SAFE could be Europe’s carrot to bring that about.

Opening SAFE funds to U.S. firms still faces some opposition in Europe. As usual, the French are keen to keep the United States out. President Emmanuel Macron, who rightly believes that Europe should be militarily autonomous but also sees EU defense spending as an industrial subsidy to benefit France, remarked that “spending should not be for [a] new, off-the-shelf kit that is once again not European.”

Critics might also point to doubts surrounding the United States’ willingness to engage in a security and defense partnership with the European Union. Given that 23 out of 27 EU states are also members of NATO, to which the United States is still committed, formalizing some sort of defense cooperation with the EU—not an alliance, and not requiring any sort of mutual defense clause—should not be a large concession for Washington. After all, the Trump administration just gave a full-fledged security guarantee to Qatar, which goes far beyond the type of low-level arrangement required for participation in SAFE.

For sure, a West based on transactionalism is a major departure from the liberal vision that underpinned a successful, decades-long partnership. But it aligns with the new political realities and could provide a good enough basis for future collaboration. Crucially, it could help sustain Europe’s security and Ukraine’s ability to fight and prevail.