WASHINGTON — A senior Biden administration official says that U.S. spy satellites detected an explosion at the Kakhovka dam just before it collapsed, but American analysts still do not know who caused the dam’s destruction or how exactly it happened.

The official said that satellites equipped with infrared sensors detected a heat signature consistent with a major explosion just before the dam collapsed, unleashing huge floodwaters downstream.

American intelligence analysts suspect that Russia was behind the dam’s destruction, the senior administration official said, speaking on the condition of anonymity to discuss operational details. But he added that U.S. spy agencies still do not have any solid evidence about who was responsible.

Seismic data picked up by the NORSAR observatory in Norway also supported the theory there had been large explosion near Kakhovka dam on Tuesday at 2:54 a.m. local time, when the structure collapsed. NORSAR said in a statement that signals captured from a station 385 miles away from the dam show clear indications of an explosion.

Engineering and munitions experts have said a deliberate explosion inside the Kakhovka dam, which is controlled by Russia, most likely caused its collapse on Tuesday. They added that structural failure or an attack from outside the dam were possible but less plausible explanations.

The administration official did not rule out the possibility that prior damage to the dam or mounting water pressure might have contributed to the collapse, but American officials believe the explosion, whether deliberate or accidental, was the likely trigger.

Experts had cautioned earlier this week that the available evidence was very limited, but they said that a blast in an enclosed space, with all of its energy applied against the structure around it, would do the most damage. Even then, they said, it would require hundreds of pounds of explosives, at least, to breach the dam.

An external detonation by a bomb or missile would exert only a fraction of its force against the dam, and would require an explosive many times larger to achieve a similar effect.

Ukraine’s intelligence agency, the SBU, says it is continuing to gather evidence to support its claim that Russia destroyed the dam. On Friday, Ukrainian intelligence released an audio recording, translated into English, that it claimed was between two Russian soldiers and was evidence that Russian forces orchestrated the destruction of the dam.

One of the speakers on the phone call says that Ukrainian forces did not cause the destruction. “It was our sabotage group,” the speaker says. “They wanted to, sort of, scare with this dam. It went not as planned, but more than they planned.”

The Ukrainians did not provide basic details that would allow independent verification of the tape, including who the participants were, why the speaker might have known what happened and why anyone might have been listening to this particular call.

Artem Dekhtyarenko, press secretary for the SBU, said in a written message that the call happened on Thursday, but that other details, such as the speakers’ locations and identities, were being withheld because “this record is an element of criminal proceedings.”

Russian officials have offered a series of different explanations for the destruction, including accusing Ukraine of sabotage, without offering evidence or explaining how Ukraine would have gained access to the dam.

Marc Santora and Gabriela Sá Pessoa contributed reporting from Kyiv.

I mean that’s usually what happens when terrorists blow up something

I find it interesting that we publically entertain the idea that it wasn’t Russia clearly blowing up the dam to cause unbelievable suffering because the pain causes Putin and his buddies pleasure. Like, we all know it was Russia. Why would anyone suspect anyone else? Russia’s word is so low at this point, that Zelenskyy and Biden could come out live on MSNBC, Fox News, PBS, the BBC, Al-Jazeera, and ESPN showing them shooting Ukranian kids, and I would wonder how it’s Russia really doing it.