- Russia appears to control Ukraine's Zaporizhzhia nuclear power plant after an attack on Friday.
- But "a great concern" is who's actually running the plant now, a senior US defense official said.
- The US said it hasn't detected any radiation increase after a fight took place outside the facility.
Ukraine's Zaporizhzhia nuclear power plant appears to be in Russia's control after its forces attacked early on Friday, a senior US defense official said.
But the official noted it's "a great concern" who is actually running the plant.
"We are in no position to refute claims that [Russian forces] are in control of the nuclear power plant, but we don't know exactly right now what that control means and what it looks like," the official said during a US Department of Defense briefing on Friday.
The US official said it's unclear what control over the nuclear plant actually looks like now, what sort of expertise those in power might have, and "what their intentions are" in the near future.
"I mean, all that is a great concern," the official said. "…We just don't know, and frankly, that is one of the things that concerns us about it."
Russian forces on Friday attacked the nuclear plant — Europe's largest — and Ukrainian officials eventually confirmed that the Russians were in control.
Ukrainian civilians had previously tried to block a road leading to the plant in an attempt to deny Russian forces an easy passage.
Oleksandr Starukh, the head of the Zaporizhzhia regional military administration, confirmed that a fire started during intense fighting around the plant, but that the blaze was "localized."
US Department of Energy Secretary Jennifer Granholm said in a tweet that there were "no elevated radiation readings near the facility," and that the plant's reactors were being "safely shut down."
The International Atomic Energy Agency said that the fire did not impact any "essential" equipment, and plant staff were taking "mitigatory actions."
'Russia is destroying critical infrastructure'
US Ambassador to the United Nations Linda Thomas-Greenfield said that nuclear facilities "cannot became a part of this conflict," and urged Russia to avoid attacking any other reactors in Ukraine.
"Russia is destroying critical infrastructure, which is denying people drinking water to stay alive and gas to keep people from freezing to death in the middle of winter," she said.
Ukrainian President Volodymyr Zelensky addressed the incident in a Telegram video on Friday, and urged people not to avoid a possible repeat of the 1986 Chernobyl nuclear disaster.
"I address all Ukrainians, all Europeans, everyone who knows the word 'Chernobyl,' everyone who knows how many victims that explosion of a nuclear plant brought," Zelensky said.
Russian forces seized the remains of the Chernobyl plant last week and, after Zaporizhzhia, the US official said there were no indications that Ukraine's three other plants have been occupied.
"We have not seen similar moves on other Ukrainian nuclear power plants," the US official said.
But, the official added, "this attack that happened just speaks volumes of the recklessness here of the Russian invasion and the potential additional damage and destruction that could have resulted from this attack."