KYIV, Ukraine—Protesters flocked to Kyiv’s central square, the Maidan, by the thousands Sunday to oppose Ukrainian President Volodymyr Zelenskyy’s gambit to make a major concession to Russia for the sake of restarting peace talks to end the war in the nation’s eastern Donbas region.

Along an entrenched front line in the Donbas, after five and a half years, Ukrainian troops remain engaged in daily combat against a combined force of Russian regulars, pro-Russian separatists, and foreign mercenaries. Despite a February 2015 cease-fire, the war is ongoing and has killed more than 13,000 Ukrainians.

To break the deadlock, Zelenskyy recently approved the so-called Steinmeier Formula—a controversial measure to hold elections in the two separatist territories in the eastern warzone.

The move, however, sparked protests across Ukraine, demanding that elections not go forward in the Donbas until all Russian troops have left.

Many protesters were also worried about the potential fallout from an American political scandal over a July phone call between President Donald Trump and Zelenskyy.

Some were left worried about the durability of American support, which many Ukrainians say is vital in their country’s defense against Russian aggression.

Play the video report above.