In October 2003, Russian special forces stormed a plane in Siberia and arrested me. I spent the next 10 years imprisoned at the behest of Russian President Vladimir Putin on politically motivated, trumped-up charges.  On Dec. 20, 2013, Putin released me — but he continues to hold Russia and the world hostage to this day.

Putin has transitioned from corrupt autocrat to expansionist fascist dictator, heralding a global rise in tyranny and populism and a more dangerous, less free world. Putin cannot be appeased. He must be defeated.

Within months of my release, during the 2014 Sochi Winter Olympics, Putin invaded Ukraine. He could not tolerate the emergence of a vibrant, young democracy aligned with European values on his doorstep, so he attacked, seizing Crimea, backing separatists in Donbas and spreading lies, disinformation and confusion. The West’s woefully inadequate response meant that Putin thought he could get away with more and paved the way for the full-scale invasion of 2022.

Putin must be defeated in Ukraine, or he will not stop there. Western powers have armed Ukraine just enough for it not to lose but not enough for it to win decisively. President Biden recognized the insufficiency of this approach when he announced a $61 billion military aid package for Ukraine in October.

When Congress stepped in to play politics with global security, delaying the aid package, Ukrainian President Volodymyr Zelensky said Putin was seeing his “dreams come true.” And Putin’s dream today will be the West’s nightmare tomorrow.

Some who talk tough about putting America’s domestic interests first will go down in history as Putin’s appeasers. Those advocating peace talks with Putin are either naive or dishonest. They would reward an expansionist dictator’s aggression against his neighbor. He would use negotiations to buy time, so he could restart the fight on his own terms at a future time of his choosing. And the next state he attacks could be a NATO member.

The success of the West over the past 300 to 400 years is based on freedom: individual freedom and freedom of trade, expression and ideas. Today, freedom is being attacked from without and within. From the outside, dictators, bullies and terrorists have been emboldened by the West’s unwillingness to resist them. From within, populists and demagogues have been playing fast and loose with democratic norms.

The West’s success, meanwhile, has become its Achilles’ heel: The comfortable life Western societies enjoy is resulting in a lack of appetite for the sacrifices required to defend the freedom on which that quality of life depends.

Freedom becomes taken for granted, leading to attacks on freedom of speech and thought. But freedom and human rights are not something that, once given, can never be lost. If Western powers refuse to pay the price to protect the freedoms and rules that underwrite their prosperity today, the price will be far higher tomorrow.

The consequences of Western inaction can be seen worldwide: The humiliating retreat from Afghanistan. Western dithering over Syria, enabling Russia, Iran and terrorist groups to plunge large swaths of the Middle East into chaos. Hamas’s despicable Oct. 7 attack against Israel also can be seen in this context — years of perceived Western weakness had emboldened evil.

China, with its own imperial ambitions and Taiwan in its sights, looks on. So does Iran, as it supplies Russia with drones and missiles and continues to seek a nuclear weapon.

Defeating Putin in Ukraine is essential and will ensure his defeat at home. Russians must prepare for what comes next. Those of us in the democratic opposition are labelled “foreign agents” by the Kremlin. In Russia, we are routinely locked up — an approach to justice for which I was a guinea pig. My friend and colleague Vladimir Kara-Murza, who was the vice chair of Open Russia, an organization I co-founded, is in jail, sentenced to an absurd 25 years. Alexei Navalny faces ongoing show trials, though at the time of writing, his condition and whereabouts are unknown.

This month, the Russian Anti-War Committee I co-founded with Garry Kasparov was added to the register of “undesirable organizations.” Open Russia has long been on the list, as has my philanthropic foundation. Yet we will continue to strive to advance education, independent media, civil society and human rights in Russia, as well as to work with Russians who have fled Putin’s tyranny. And we call on the West to work with us as legitimate representatives of the Russian people, determined to develop a future Russia that is free at home and peaceful abroad.

If Putin is not defeated in Ukraine, however, the consequences will be felt not just by Ukrainians or Russians but by a free world that will have failed in its responsibility to stand up to aggression.

A U.S.-led West still has a chance to protect itself and its allies, but it will need to pay a price — and not just a monetary one. Today the price is weapons, but if that price is not met, tomorrow it will be the mobilization of your children. If the West does not act decisively now, then the decade in which I regained freedom could prove to be the decade in which the West surrendered it.

Mikhail Khodorkovsky, former head of the Russian oil company Yukos, served 10 years in a Russian prison and now supports political opposition projects in exile. He is the author of  “How to Slay a Dragon: Building a New Russia After Putin.”

The article was first published in The Washington Post