On March 18, the airplane carrying the vice president of the United States landed in Vilnius. Joe Biden had flown into the Lithuania capital from Warsaw, where he had just held talks with the leaders of Poland and Estonia. The presidents of Lithuania and Latvia were waiting in Vilnius. One does not need to be an expert in international affairs to understand that Biden’s trip to Central and Northern Europe was prompted by Russia’s military aggression in Ukraine and the subsequent annexation of Crimea—a brutal breach of international law, unprecedented in modern-day Europe. Indeed, Europe had not experienced anything similar since the 1968 events in Czechoslovakia.

Of course, one should strive to maximize peace and order; however, this must be based on internationally recognized standards—not just those of one country. Russia has sought to justify its behavior as defending ethnic Russians. However, that begs the question—defending them against what? Against the way the people of independent Ukraine came out to the Maidan and exercised their sovereign rights to protect their democracy and freedom of choice in deciding how to shape their future? Or was the dismantling of the post–Cold War European order a deliberate step to restore the old European order of the twentieth century—the arrangement outlined in a speech on Vienna’s Heldenplatz 1938, in which the fates of individuals and states are determined by external geopolitical calculations and ethnic identity?

Moscow’s decision to annex the territory of a sovereign neighboring country in the name of such geopolitical considerations is not just Ukraine’s problem—it is a challenge to European and global security. In his March 26 speech at the Palais des Beaux Arts in Brussels, U.S. president Barack Obama stated, “To be honest, if we defined our interests narrowly, if we applied a cold-hearted calculus, we might decide to look the other way... Our own borders are not threatened by Russia’s annexation. But that kind of casual indifference would ignore the lessons that are written in the cemeteries of this continent....And that message would be heard not just in Europe, but in Asia and the Americas, in Africa and the Middle East.”

It gives one pause to realize that in the twenty-five years since the fall of the Berlin Wall and the collapse of the Soviet Union, we’ve arrived full-circle to the very outcome that we sought to avoid—a European state can violate international norms without any pretext, ordering its armed forces to enter a neighboring country, hoping that the international community will simply swallow it. The shock waves created by Russia’s action are so impressive, that it’s quite natural to ask a question how exactly the international community—and the security structures that it has created, including NATO—should respond to the given situation. What is the strategic role and responsibility of NATO in this situation?

To my mind it is really very simple and straightforward—in every situation that threatens its allies, NATO must collectively guarantee the security of its members. In this situation there is no distinction between large and small allies—all are allies. The military capabilities of the United States are sufficient to allow it to provide its own security. However, if the U.S. were to choose to embark upon such a path, instead of utilizing the collective-security system that NATO offers, it is my opinion that the United States’ political influence on the world stage would be significantly curtailed. This, in turn, would have an adverse effect on U.S. security. Mr. Biden’s recent visits to Warsaw and Vilnius thus increased the security not only of NATO’s Northern, Eastern and Central European states, but also of the United States. His visits served as a manifestation of support for those Americans and Europeans striving to strengthen the Trans-Atlantic relationship on the basis of clear and commonly shared values—one of the most efficient ways of banishing the ghosts of the Heldenplatz.

It is deeply symbolic that this spring we celebrate the policy of NATO enlargement that significantly increased European security and brought us closer to a Europe that is whole and free and at peace. Joining the Alliance was a free choice of each and every new European democracy—nobody forced us to join. However, history had taught us that by remaining outsiders, we encouraged Europe’s undemocratic, destructive forces to adopt undesirable policies towards us.

That is why the choice that democratic NATO member-states must make in situations such as the annexation of Crimea is either to fulfill NATO’s mission—by increasing the security of those members who find themselves the most exposed along NATO’s outer flank—or to do nothing, in the hope that doing nothing will somehow lead the aggressor state to realize the folly of its ways and to become a better state. The cost of the first option will be high, but the cost of the second option will be catastrophic.

Latvia and the other Baltic states are among the smaller NATO allies. But compared to the United States, the absolute majority of Alliance members are also smaller, not to mention the relative size of each ally’s defense-related expenditures. Nevertheless, Article Five of the Washington Treaty does not distinguish between large and small NATO member-states. All NATO allies are under identical mutual collective-security obligations. The strategic importance of the Baltic countries to the United States is no smaller than that of any other NATO country. It is especially important to emphasize this now, when Europe is facing seemingly long-forgotten security challenges, when there may be a temptation to divide NATO allies into two categories: important and unimportant allies. In other words, drawing a distinction between those NATO allies who are “worth defending” versus those who are best thrown to the lions. This is a dangerous way of thinking—to trace the consequences of it, one must only look back a couple of generations. If this kind of thinking was ever to regain dominance, life would quickly become unbearable, both for those allies who some might be tempted to designate as “not worth defending” as well as those who would be lucky enough to be designated as “worth defending.” In this kind of world, a country’s membership in any particular geopolitical grouping would become completely irrelevant, and the entire concept of international security would become null and void.

When smaller NATO allies such as Latvia send their soldiers to places like Afghanistan, those Latvian soldiers do not distinguish between allies whose lives are “worth defending” and allies whose lives are “not worth defending.” On the battlefield, there are no such distinctions. That has been proven beyond any shadow of a doubt by those heroic Latvian soldiers who have been awarded prestigious U.S. Army honors in recognition for their valorous service as part of the International Security Assistance Force in Afghanistan.

That is why Mr. Biden’s recent visit to Lithuania and Poland holds a special meaning. Through his visit, the U.S. affirmed—also beyond any shadow of a doubt—its commitment to the security of the Baltic countries and Poland within the framework of Article 5 of NATO’s Washington Treaty. What to do next? In the context of the early lessons learned from Crimea, parallel to seeking a deescalation of the situation in Ukraine via a diplomatic solution, the United States and NATO allies should do what must be done in such situations: consolidate the security of NATO allies. This must be done by promptly perfecting their specific military capabilities, strengthening NATO’s airspace-control and air-defense systems and continually conducting NATO military training related to collective defense.

Latvia is an ideal place for U.S. soldiers to strengthen their skills and abilities. Along with the already-consolidated Baltic Air Policing Mission, which is being executed through the cooperation of NATO member-states, such steps would serve as a necessary and clear answer to the legacy of Heldenplatz speech. As European history has demonstrated on numerous occasions, an aggressor chooses his goals based on an assumption as to whether or not his aggression will be forgiven. Even if we do not yet have full clarity regarding the true goals of those who are carrying out the current aggression against Ukraine, and regardless of their ultimate goals, NATO must take collective steps that will increase the security of all NATO allies, bar none.

Andris Razans serves as Ambassador of Latvia to the United States.