When Russia annexed Crimea in 2014 and began arming and deploying separatists in eastern Ukraine, it launched the most significant foreign invasion of European soil since World War II. Its goal was to create a rump state of Ukraine, smaller than the country now is, and that would serve as a proxy for Russian control.

The Kremlin anticipated resistance but underestimated it. Its preparations for the war focused on identifying collaborators in Ukrainian society who could run occupying administrations in areas like Kherson, where Moscow has a military base. It also relied on Ukrainian dissatisfaction with the corruption and oligarchic economy that had plagued the government. But even the supposedly apolitical have fought back or sounded the alarm about Putin’s deceptions and violence.

In the years leading to the invasion, Ukrainians grew closer to NATO. They held annual joint exercises, were named one of six enhanced opportunity partners, and affirmed that they wanted to eventually join the alliance as full members. The decision by the Ecumenical Patriarch of Constantinople to recognize and grant autocephaly (independence) to Ukraine’s Orthodox church was another sign of a growing desire for Ukraine to become less Russian and more Western.

Nine months into the war, however, the odds that Russia will be able to hold onto a large part of Ukraine appear to be fading fast. If the conflict does drag on into a long-term stalemate, it will be a testament to Ukraine’s resolve and its enduring strength. The Finns have a word for this fierce combination of will and determination: sisu. It is what Ukrainians display every day, despite Russia’s relentless rain of missiles and drone strikes on their apartment buildings, schools, and hospitals.