STORY: The dam for a massive reservoir in southern Ukraine has been destroyed on a river that separates Russian and Ukrainian forces, surging floodwaters onto the battlefield, forcing villages to evacuate, and transforming the front line just as Ukraine appears to be carrying out its long-awaited counteroffensive.
Russia has controlled the Nova Kakhovka dam since early in the war although Ukrainian forces captured the northern side of the river last year.
Flooding had begun in some towns as of Tuesday morning.
The dam is 30 meters tall and once held back a reservoir 150 miles long, which supplies water to Crimea and the Zaporizhzhia nuclear plant, both of which are also under Russian control, although the U.N.'s nuclear watchdog says there's no immediate threat to the latter, and is monitoring the situation.
Both sides are blaming the other for the breach and neither has offered immediate evidence of their claims.
President Volodymyr Zelenskiy says Russian forces destroyed the dam from the inside in what he calls a deliberate war crime, and that about 80 settlements are in the flood zone.
The Ukrainian military says the objective was to prevent Ukrainian forces from attacking Russian troops on the other side of the river.
Russian-installed officials are giving conflicting accounts of what happened. Some are blaming Ukrainian shelling. Others say the dam burst on its own.
This footage is from the Russian-installed head of the regional government.
Russian state media, quoting the Russian-installed governor, reported that 14 settlements were at risk in the Kherson region and 22,000 people.
The Kremlin says Ukraine sabotaged the plant to distract attention from what it calls its faltering counteroffensive.