Ukraine’s former defense minister Mykhailo Fedorov called for an election Tuesday despite the country’s prolonged war with Russia, in what is seen as the largest challenge to President Volodymyr Zelenskyy’s power since the start of the conflict.

Zelenskyy imposed martial law, which prohibits elections from being held, when Russian forces invaded the country in February 2022.

In a video posted on YouTube, Fedorov said, “Democracy cannot be held hostage by Russia,” and called for a “legal, safe and realistic mechanism that will allow Ukraine to restore a full democratic process even amidst a prolonged war.”

“We are fighting precisely because we want to remain a free European state,” he added.

Before his ouster last month, Fedorov had helped design Ukraine’s strategy seeking to bring an end to the war by turning to drones and robots to beat back its larger adversary.

Zelenskyy fired Fedorov in mid-July, citing an unsolvable feud between Fedorov and Zelenskyy’s top general, Oleksandr Syrskyi. The move sparked weeks of protests from thousands of people across the country, criticizing the removal of the widely respected minister.

Fedorov was credited with turning the tide of the war in Ukraine’s favor, increasing Ukraine’s strikes deep into Russia tenfold and bolstering its domestic arsenal.

In an exclusive interview with CBS News just days before he publicly called for an election to be held, Fedorov said the protests over his removal are a sign that the Ukrainian people support democratic values and that Ukraine is fighting for its freedom.

In the YouTube video, Fedorov did not elaborate on his own plans in the event of an election, but he has previously said he would only return to the government as defense minister.

The former defense minister acknowledged the difficulties of holding a vote during the war, including how to ensure soldiers, people who live near the front line and Ukrainians who fled the war can cast their ballots.

“This is complex. … But complexity does not mean impossibility,” Fedorov said.