In 1948, when I was five years old, I spent seven months in a bomb shelter while Jerusalem was under siege by the Jordanian Legion. I missed a year of kindergarten.

Twenty-five years later, as an artillery officer in the Israeli Defense Forces, I participated in laying siege to the city of Suez in Egypt and in the encirclement of the Egyptian Third Army in the Sinai during the Yom Kippur war of October 1973. When we soldiers inquired how long this siege was going to take, we were told: “A week, a month, a year, who knows? They’re negotiating.”

Fortunately for all involved, a ceasefire was quickly negotiated, and by January we were sent home.   

“The worst policy of all is to besiege walled cities,” the Chinese general Sun Tzu said in The Art of War in the sixth century B.C. As instruments of war, sieges inflict a brutal toll on civilians and rarely achieve their military objectives. So when you hear that Russian President Vladimir Putin has ordered the Russian army to lay siege to major Ukrainian cities like Kyiv and Kharkiv, remember that history, even recent history, confirms again and again that a committed urban population, given time and sufficient supplies of food, medicine and arms, can be all but unconquerable.

When a war becomes an urban war — when invaders move from open countryside to crowded streets — the advantages of size, air cover, or more sophisticated weaponry do not hold. That’s why the best hope for Ukraine’s hard-won democracy and self-determination lies with its cities. The Ukrainian people cannot lose if they can make it as difficult as possible for the Russian army to enter and occupy them. In this, the form and character of their cities can and will come to their aid.

As an urban scholar and practitioner, I have spent my career studying cities — mapping and measuring their growth, and getting involved in designing and implementing numerous policies, plans and projects in cities near and far. For me, they are a subject of endless fascination, most of all because of their infinite complexity — millions of people making billions of unrelated decisions on their own, day in and day out, and it all comes together somehow. Cities “work” because of their innate resilience; they have an inexhaustible ability to reinvent themselves, to regenerate their civic spirit, to fashion and refashion innovative solutions to crises, and even to rise from the ashes.