Satellites equipped with infrared sensors detected a thermal event indicating a major eruption shortly before the dam collapsed, releasing massive flooding in the Dnieper River, the official said.
US intelligence analysts suspect that Russia was behind the destruction of the dam
said a senior government official. He added that US intelligence agencies still have no concrete evidence of who is responsible.
A government official did not rule out that earlier damage to the dam or a rise in water pressure may have contributed to the collapse, but U.S. officials said the cause was a deliberate or accidental explosion.
Experts warned earlier this week that the available evidence was scant, but said an explosion in a confined space could cause more damage. Even at this level, at least several hundred kilograms of explosives would be required to breach the dam.
An external detonation of a bomb or missile would exert only a fraction of its energy on the dam, and much larger explosives would be required to achieve a similar effect.
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