Russia will slow Ukrainian troops' advance in the south by just two weeks if it blows up the vast Kakhovka dam, but such a move would flood territory occupied by Moscow and lose it a vital water canal for annexed Crimea, Kyiv's military spy chief said.
Kyrylo Budanov made the comments to Ukrainska Pravda in an interview published on Monday after President Volodymyr Zelenskiy said last week Russia had mined the hydro-electric dam on the Dnipro River and was preparing to blow it up.
Russia, whose troops are on the back foot in the occupied Kherson region which Kyiv is trying to recapture, has itself accused Ukraine of plotting to blow up the dam, a step that would unleash a devastating flood.
Budanov, head of the Defence Ministry's Main Directorate of Intelligence, said the dam had been only partially mined by Russia and that destroying it completely would require many tonnes of explosives.
Such a move would create an environmental catastrophe and also cause new headaches for Russia, whose forces would have to retreat to Crimea, he said.
"They will get a total flooding of the (Russian-occupied) left bank of Kherson. They will lose even theoretically the possibility of supplying water to the North Crimean Canal, to Crimea...," he said.
"Of course, they would complicate our advance for a certain period of time. And this, by the way, is not a very long period of time, around two weeks or thereabouts," Budanov said.
Ukraine blocked fresh water supply to Crimea via the North Crimean Canal after Russia seized the arid peninsula in 2014. After Russian forces seized new swathes of southern Ukraine this year, they immediately restored the water supply from the reservoir via the canal.
Only partially destroying the dam would still complicate Ukraine's advance, lead to a partial water spill but maintain water supply via the North Crimean Canal, Budanov said.
Budanov said blowing up the dam would also "destroy the possibility of the existence of the Zaporizhzhia nuclear power plant because this facility is inextricably linked to it".
The nuclear plant, Europe's largest, has been occupied by Russia for months and is located near the reservoir.
Budanov said he expected Ukraine to recapture the city of Kherson - the only Ukrainian city Russia has captured intact since launching its invasion eight months ago - by the end of this year.
(Writing by Tom Balmforth; Editing by Gareth Jones)
