This post was co-authored with Elizabeth Barnes, an International Relations student at the University of St. Andrews in Scotland.

The United Kingdom’s decision to exit the European Union is an opportunity for the United States, as well as United Kingdom, to rethink their relationships with Europe. In response to Russian pressure on Eastern Europe, the United States has been increasing its military presence from the Baltic to the Black Sea. At the same time, there are many in the United States who question the Europeans’ willingness to share the burden of their own defense. With the exception of the United Kingdom and the United States, as well as some smaller member states near Russia’s border, most NATO members do not meet the alliance’s two percent of GDP goal for defense spending. Despite much foot shuffling, it is not likely that many will in the foreseeable future.

The funding dispute has even spilled over into the American presidential campaign with Donald Trump suggesting that the United States could withhold its defense of NATO members who fail to meet the alliance’s funding goals. Many former senior officials from both Republican and Democratic administrations of the past are appalled that anyone would think about NATO in such crass terms. They remind all that Article V of the NATO Treaty obligates members independent of the scale of their military effort to come to each other’s defense. And yet, it does seem a bit strange that United State, which is far from Eastern Europe’s problems, is expected to be in Europe’s very first line of defense while NATO partners living nearby can’t find the resources to do their share.

Of course, the United States does have a vital interest in preventing Europe from falling under the domination of any hostile power. This interest led us to fight in Europe in both World Wars and to stay through the Cold War and beyond. But there is also an interest in not making American taxpayers the security subsidizers of rich Europeans. It is unclear why the answer to increased tensions along Europe’s eastern frontier requires the United States to move more combat units to the continent. In fact, there is an argument that the way to get the Europeans to get serious about their own defense is not to set goals that never fall due, but rather to pull American forces out of Europe instead of putting them back as is the current plan.

Leaving Europe now would surely cause panic, not constructive action. There is a halfway. The U.S. military should pull back to the North Atlantic’s first island chain—namely, Britain and the Azores where America currently has bases. It is there that we should put reinforcements with the expectation that the European members of NATO would be the forces that guard Europe’s eastern frontier. If they offer more forces for that purpose and increase their defense budgets, the United States could do more. If they are unwilling to do more, then U.S. forces could withdraw to the Atlantic’s second island chain which includes Long Island and Bermuda.