However the military operations might unfold in Ukraine, we are on the brink of a world transformed. The post-Cold War security architecture has crumbled. Nobody can with certainty predict the effects, but they will reverberate for decades.

Until this morning, all too many Europeans viewed war as unthinkable and saw themselves as spectators to conflict. Now conflict has come home. As missiles rain on Ukraine, Europe’s leaders have condemned the actions and promised a response.

“We call on Russia to immediately cease its military action and choose diplomacy,” said the secretary general of the North Atlantic Treaty Organization, Jens Stoltenberg.

Yet diplomacy in the form of talks is not an alternative to war. President Putin has also made clear that he is not interested in more talks — and is not interested in the “international order” as the West understands it. He seeks his own kind of order and has waged what could be Europe’s largest conflict since 1989, perhaps 1945, to get it.

Countries like Poland and the Baltics — all too familiar with Russian aggression — have long warned of this, only to have been accused of being alarmists, or even paranoid. They could now yet emerge leaders of a new European security stance.

As some German leaders lamented Europe’s lack of preparedness and diplomatic missteps, Lithuania has today become host to a Belarus government-in-exile led by Sviatlana Tsikhanouskaya. The last government-in-exile in Europe was of Poland.

When in 1990 Lech Walesa was sworn into office as a democratically elected president of Poland, the sash of office he was handed came not from the outgoing communist puppet regime but from the Free Polish government that had been, since World War II, operating from a townhouse at London.

Today’s unfolding calamity may well reverberate far beyond Europe — to, say, Asia and the Middle East, where autocratic leaders in Communist China and Iran eagerly wait to expand their spheres of influence. Western reactions to Russian aggression will almost certainly color how Beijing proceeds in the South China Sea and on Free China. 

The impact could extend also to the United Nations, where this morning, our Benny Avni reports, Ukraine, in an astonishing demarche, challenged the very legitimacy of Russia’s membership in the world body. The logic of multilateralism could yet find itself undermined, and new forms of “minilateral” alliances could emerge.

The coming days and weeks will set precedents for decades to come — of democracy and sovereignty, of what is and is not permissible among nations in the 21^st century, and of human dignity, morality, and the values for which valiant Ukrainians are now fighting and dying. 

While the blame for the current crisis is squarely on Mr. Putin’s shoulders — he is the one who gave the order to war — the ability to determine what comes next lies, still, with Western leaders. 

This requires a healthy dose of reflection. As this column has previously argued, part of the West’s folly in its dealings with the Kremlin has been its mistaken belief that the Cold War ended and power politics were a thing for the dustbins of history. Neither was ever true. Today’s events and the global realignment they herald have been unfolding for decades.

In its mistaken belief in a post-Cold War era, the West assumed a kind of secularism, in which notions of “good” and “evil” were replaced with “rational” and “irrational.” Such appeals have shaped much of the discourse around Mr. Putin’s actions in Ukraine. The possibility of pure wickedness was unfathomable.

War, though, brings its own clarity. As Western leaders now seek to determine the course of this brave new world, they will have to  think not only in terms of military tactics, economic sanctions, and political alliances. History, values, and core principles must be considered.