KIEV, Ukraine — Ukrainians stomped and chanted on the icy cobblestones. They unfurled a gigantic banner with the words “Remember Us, We Are Fed Up!” And when a government collapsed, they thought they had won.

That was nearly four years ago. Since then, frustration has again bubbled up, mostly over the slow pace of anticorruption measures by the new government. Corruption was a crucial issue in 2014, as well.

This fall, yet again, a tent protest camp has popped up in Kiev, the Ukrainian capital. Though far smaller than the Independence Square rallies of 2014, the new campaign has become the first sustained street movement since then.

For a country already plagued by economic collapse, a war with Russian-backed separatists and, over the past year or so, a string of assassinations and attempted assassinations in the capital, the several hundred protesters and their tents add another unpredictable element to Ukrainian politics.