As President Donald Trump prepares for what many reasonably fear could be a diplomatic train wreck at the July 11-12 NATO summit in Brussels, the odd truth is that when it comes to transatlantic security, the president actually has a pretty good story to tell.


In the past 18 months, the United States and its NATO partners have continued to lift their game, bolstering their collective capabilities aligned against the Russian threat, increasing their defense resources and developing new initiatives to address NATO’s operational shortcomings.


There’s a lot to commend. By agreeing last month to develop a substantial NATO force to deploy by air, land and sea within 30 days, the allies (who will formalize the agreement at the summit) took a big step toward expanding and strengthening their reinforcement capabilities. The alliance will also augment its ability to make decisions in critical areas by establishing two new military commands - in the United States and Germany - focusing on maritime security in the Atlantic and military mobility in Europe, so forces can get to the fight with fewer logistical hurdles. NATO will also assume a more substantial training mission in Iraq and elevate cyberthreats in its planning and operations.


There’s even good news on defense spending: Almost every ally is doing more, albeit not at the same pace. However much grumbling one hears, the trend is headed in the right direction. And while past U.S. presidents have also called for European partners to increase their military budgets, NATO diplomats concede that Trump’s singular obsession with this issue has made a difference.


The summit should therefore be a moment to take a victory lap by enshrining these decisions and establishing a road map for the future. Instead, for the Europeans, the measure of success at the meeting has been reduced to getting through two days relatively unscathed by a presidential rant or tweetstorm. So the news in recent days about letters from Trump berating European allies to spend more on defense is an ominous sign.


What makes this so puzzling is that the same president who rarely hesitates to take credit or to claim that something is successful without much supporting evidence - as with his assertions of instant success with North Korea - seems so determined not to boast of victory in this instance, though there’s plenty to crow about. Even worse, Trump seems likely to be more effusive about his summit with Russian President Vladimir Putin just a few days later.


Some of the problem is that, apart from the issue of European defense spending, Trump has appeared disengaged, uninterested in the details of military mobility or command structure. The NATO agenda has been driven by other corners of the administration, particularly in the Pentagon. One wonders if Trump is even aware that this year his Defense Department released a strategy that prioritized fortifying security alliances such as NATO.


Now Pentagon planners are as worried as the Europeans that the commander in chief will spoil their success. The trouble might take the form of a presidential temper tantrum or a refusal to sign the summit communique (as with the recent Group of Seven fiasco), or a Trump proposal that Putin be allowed to join NATO summits as Russian presidents have in the past, or a threat to pull U.S. forces out of Germany (as the Pentagon has been asked to look into).


That highlights another problem: From Trump’s perspective, America’s security approach to Europe has not been disruptive enough. The fact that the positive changes in NATO today stem from summits held during the Obama administration is probably another reason Trump is reluctant to claim success. If the president wanted to herald a bipartisanship achievement, this is where he could.


But don’t hold your breath. Trump seems more interested in projecting macho dominance over his European partners or punishing them for “cheating” the United States over the years. That NATO is a unique asset to America’s global power seems a matter of indifference to him - after all, how many security allies do China and Russia have?


Four years ago in Wales, NATO leaders met at a moment of great uncertainty. Just months after Russia’s war against Ukraine had started and as the Islamic State crisis exploded, there were many concerns about the ability of the United States and Europe to face these twin challenges. Yet the response must largely be considered a success: Putin has been stymied, and the Islamic State’s “caliphate” was routed. As the NATO leaders plotted their course, no one imagined that a few years later the greatest threat to the alliance’s unity would come not from Moscow or Mosul, or some weak-kneed European capital, but from Washington.


Derek Chollet is executive vice president of the German Marshall Fund of the United States and a former assistant secretary of defense for international security affairs during the Obama administration. He wrote this for The Washington Post.