The rapid collapse of the Yanukovych regime in Ukraine and the international crisis now unfolding in the region once again highlights the inherent instability of authoritarian regimes that disregard the legitimate aspirations of their own people. Too often, independent voices in the post-Soviet space that challenge authoritarian leaders—and the corrupt elites they support—face violent repression when the status quo is threatened. This is especially true in Belarus, where the Lukashenko government, in power for nearly 20 years, has continued a crackdown that began after the country’s fraught 2010 presidential contest.

As the European Union and its member states struggle with how to handle such undemocratic neighbors, it is clear that a consistent and forceful message is needed: respect for fundamental human rights is a critical component of a prosperous and secure Europe; there is simply no place for the repressive policies of the past.

While international attention is rightly focused on the events now unfolding in Ukraine, it is also critical to understand how such popular movements are viewed by 20th Century regimes that tightly cling to power. In an increasingly interconnected world, citizens who demand their basic rights in one corner of the world threaten dictators around the globe who fear similar movements at home. But while some governments may seize this moment to increase pressure on political activists and the press, in Belarus, the crackdown never really ended.

On December 19, 2010, hopes for democratic reform in Belarus were extinguished when a flawed election kept Alexander Lukashenko in power. When the polls closed after yet another election that failed to meet international standards, thousands of Belarusian citizens gathered in downtown Minsk to demonstrate in support of their democratic rights. Police responded by beating and arresting hundreds of peaceful protesters and opposition leaders, using as a pretext the actions of a few individuals widely believed to be government provocateurs. In the end, the government criminally charged six opposition candidates and 30 of their supporters with inciting the demonstration.

Exacerbating the politically motivated charges was the brutal treatment that the activists faced once in custody. The government denied them access to their families and lawyers and subjected them to repeated beatings, extreme cold, stress positions, sleep deprivation, and constant threats. In the end, interrogators only wanted one thing—a confession they believed would justify the repression.

When the government found it necessary to hold trials, the proceedings failed to meet even basic due process standards and, like the election, were widely dismissed as unfair by independent observers. The government disbarred defense lawyers, restricted access to case files, failed to investigate mistreatment, and ultimately could not produce any evidence that the candidates incited any harm to people or property. Undeterred, the Lukashenko regime handed down prison terms of up to six years.

Of those candidates prosecuted during the crackdown, only Mikalai Statkevich remains in prison, though others still face restrictions on their civil and political rights. The government sentenced Mr. Statkevich to six years in prison, and even now three years into his sentence the government continues to pressure him to sign a pardon request. Claiming that he violated prison rules, authorities sent him to a stricter prison facility and have periodically limited his access to family visits because he refuses their demands.

The international community has largely condemned the crackdown. The United States reauthorized its sanctions in 2011. The European Union has maintained a series of “restrictive measures”, especially through visa restrictions and asset freezes, aimed at pressuring the Lukashenko regime to release political prisoners. Notably, Štefan Füle, the European Commissioner for Enlargement and Neighborhood Policy, has emphasized that any improvement in Belarus’ relations with the EU depends on the release of all political prisoners.

Despite such efforts, however, Mr. Statkevich remains in prison, and the Belarusian government has continued imprisoning its critics, either through administrative detention or fabricated charges. The most prominent example is the continued imprisonment of human rights defender Ales Bialiatski on politically motivated tax evasion charges.

While some officials encourage “constructive engagement” with the Belarusian government, Lukashenko’s own representatives have failed to engage honestly when given the opportunity. After the European Union suspended visa restrictions on Belarusian Foreign Minister Vladimir Makey in the run-up to Eastern Partnership talks last November, the Foreign Minister used the opportunity, not to engage, but to deny the existence of political prisoners in his country.

Lukashenko has responded to the events in Ukraine by asserting his authority and tighten his grip on power. The international community can, and must, do more to help the people of Belarus secure the dream of a free, democratic, and thriving homeland. The stakes are now strikingly clear and the existence of a dictatorship in Europe must no longer be tolerated.

The international community must speak with one voice in demanding the release of all prisoners of conscience. Mr. Statkevich must be released immediately—without condition and without being forced to sign a pardon request or make a false confession.

Ales Michalevic is a Belarusian political activist and former presidential candidate who was imprisoned during the 2010 crackdown before seeking asylum in the Czech Republic. Maran Turner heads Freedom Now, a legal advocacy organization that works to free prisoners of conscience, including Mr. Statkevich.