NATO and U.S. flags flutter as a U.S. Air Force F-22 Raptor flies over the military air base in Siauliai, Lithuania, on April 27. (Ints Kalnins/Reuters)

Philip M. Breedlove is NATO’s Supreme Allied Commander Europe and commander of the U.S. European Command.

When I became Supreme Allied Commander Europe (SACEUR) and commander of the U.S. European Command in May 2013, there was discussion in certain circles about the utility of NATO. I felt those discussions were completely without merit and that there was no need to engage. In my mind, and in the minds of the people who work in, around or with NATO, the utility of the alliance is self-evident. This was tantamount to having a discussion about the utility of the sun. The NATO alliance is arguably the most critical linchpin supporting stability on the continent that is home to the world’s largest integrated economy — and, incidentally, on the continent that has in the past century or so spawned the world’s most destructive conflicts.

As I wrap up my time as SACEUR, a tenure marked by the invasion of a neighboring state by Russian Federation forces, it seems utterly implausible that there are still those out there, some of them influential figures, who doubt the utility of NATO. So I feel the need to explain to my fellow countrymen why the United States absolutely needs NATO — a NATO that is strong, resilient and united.

In the century before I became SACEUR, approximately 100 million people died as a result of World Wars I and II[. Additionally, Europe was caught in a vicious cycle of violence where, from the Franco-Prussian wars to WWI and then WWII, the results of one war fed directly into the casus belli for the next. Thankfully, after WWII, we broke the pattern. In fact, since the inception of NATO, the European continent has enjoyed its longest period without a major power conflict in centuries. Though NATO cannot take all the credit for this prolonged period of relative peace, it is no mere coincidence that Europe’s stability and prosperity have developed alongside the world’s most capable and effective political-military alliance.

Speaking of prosperity, the peace that NATO has facilitated has allowed our European allies to focus resources toward rebuilding the continent from the ravages of WWII. Europe rose from the ashes of destruction to now boast the highest gross domestic product of any continent. In terms of direct benefit to the United States, the European Union is our largest trading partner, comprising more than $698 billion in annual trade. Without NATO, those member nations would likely have maintained large and expensive standing armies not simply to protect against a potential threat from the east but also to protect against the threats that had consumed Europe from within for centuries.

An additional key contribution is NATO’s role in facilitating the peaceful transition of former Warsaw Pact countries from autocracies to thriving democracies. On the map of Europe today, recently democratic nations have far greater stability and prosperity if they are NATO members. The expense in assisting these allies to develop vibrant democracies and civil societies pales in comparison with the costs of turmoil and civil war.

Looking at NATO’s recent history, it is also important to note that an Article V, or collective defense, declaration has been made only once in the 67-year history of the alliance: in support of the United States after the attacks of Sept. 11, 2001. Since our allies’ 2003 deployment to Afghanistan, they and our partners have fought beside us, for our defense. This is an alliance that has proved its worth, in the blood of its sons and daughters.

Finally, if the naysayers still are not convinced of the criticality of this alliance, just look at the headlines. There is an arc of instability and aggression threatening our interests and our allies stretching from the Arctic, through Eastern Europe and the Middle East, and across North Africa. Only the most diehard isolationist could claim that this is not a direct threat to the United States and our interests. Our allies are on the front lines challenging Russian aggression, ungoverned and undergoverned spaces, and the world’s largest migrant crisis since WWII. Russia’s revanchist ambitions and illegal annexation of Crimea have led to the first attempt to change internationally recognized borders by force in Europe since the end of that conflict. Our allies are reacting and engaging. They have been essential in maintaining effective sanctions against the Russians and in ramping up exercises and assurance measures.

In the past two years, we have seen a reversal in the trend of declining defense budgets among our allies. Though not all are achieving NATO’s target level of defense spending at 2 percent of GDP, recent budget developments in many of the allied nations show defense spending increases. Additionally, and most significantly, allies are taking the lead. One of our newest adaptation measures in NATO is the creation of the Very High Readiness Joint Task Force. This brigade-size task force, with all necessary enablers, is ready for deployment anywhere in Europe on a moment’s notice. It is anchored around brigades provided by non-U.S. members of the alliance.

NATO has been and will continue to be the centerpiece to peace and stability in Europe. It is an institution indispensable in today’s dangerous world. We Americans cannot stand alone. Our greatest strength is vested in our partners and allies who share our dreams, our values and, yes, shoulder-to-shoulder share our burdens.