Friday marks the 100th day of the war between Russia and Ukraine. When Russian tanks rolled across the border on Feb. 24, most anticipated a brief conflict, ending with either a Ukrainian surrender or some type of negotiated peace.

Those assumptions proved false. Ukraine withstood the initial onslaught, and the war has now entered a bloody, protracted phase with no easily predictable end.

These 100 days have taught us a few things about war, peace and leadership in the modern world. Here are four of them.

Motivation matters. Napoleon famously observed: “The moral is to the physical as three is to one.” His point: No matter how many troops or cannon your opponent has, what matters most is the motivation and spirit of the respective combatants.

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After counting Putin’s tanks, planes and missiles, many predicted Kyiv would fall in three days. What they did not factor in their calculations was the resolve of Ukrainians—many not even in uniform—to fight for the freedom of their family, village and country. The media is full of stories about Ukrainian rock bands, politicians and farmers alike who took up rifles, Javelins and Stingers to repel the Russians. Conversely, there are many stories of Russian soldiers, told by their superiors that they would be welcomed in Ukraine, becoming disenchanted and demoralized when that turned out to be wrong.

There are lessons here for Taiwan and other nations caught between major powers. Never underestimate the intangibles, the things you can’t measure or count, in war.

Hard power still matters. Some in Europe had convinced themselves that society had evolved to the point that war, the kind with bullets and missiles, was a thing of the distant past. Germany had essentially disarmed its military, reduced military spending, and refused to buy even armed drones on the excuse that they were too “warlike.” Other countries, similarly, let their militaries decline into obsolescence, in favor of supporting a comprehensive welfare state.

Putin’s naked aggression shocked these nations, producing an epiphany of sorts. Within weeks, Germany reversed course and declared it would exceed the NATO benchmark for defense spending. Moreover, it will now purchase cutting-edge F-35 jet fighters.

The fighting has severely crippled Putin’s fighting force. But autocracies always value their military above all else. Once Putin gets the chance, he will rebuild his army and air force first; domestic priorities can wait. As long as autocrats like Putin, Xi and Kim hold power, the freedom-loving nations will need to maintain sufficient military forces to keep them in check.

No one will be giving up their nukes. In 1994, Ukrainians decided to give up the thousands of Soviet-made nuclear weapons left in their country in exchange for vague promises from the U.S., U.K. and Russia. The agreement, called the “Budapest Memorandum” turned out to have all the weight of Confederate money after the Civil War.

It is incontrovertible that if Ukraine had kept but a few of these nuclear weapons, Russia would have been dissuaded from invading. While the idea of a nuclear-weapon-free world is appealing, the cold truth is that, going forward, no nation will probably ever be persuaded to give up their nukes.

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Great leaders rise in crisis. A goofy stand-up comic, there was little in President Volodymyr Zelensky’s resume to suggest a man marked for greatness. Later cast as a history teacher in the Ukrainian TV show Servant of the People, Zelensky captured public attention with a profanity-laced speech against corruption. Although it was all drama, the speech generated tailwinds that propelled him to the presidency in 2019.

But it was a simple one-liner that captured the world’s attention in February. When the U.S. offered to evacuate him beyond the reach of advancing Russian troops, Zelensky responded bluntly: “The fight is here; I need ammunition, not a ride.”

Since that day, he has been ubiquitous on the world stage: addressing Parliaments and Congress, walking the streets of Kyiv and readily putting himself in harm’s way to rally his country—always in his trademark camouflage green t-shirt, foreswearing the business suit until Ukraine is free of Russians. It’s a powerful reminder of the potential within all of us to rise to the circumstances.

Sadly, we are probably months away from any resolution of this conflict. More will die, and additional lessons will be learned. Our hearts are with Zelensky and the brave Ukrainians. But it is not too early to start to draw insights that will help guide us in maintaining our own national security.