Continued shelling around the Zaporizhzhia nuclear power plant has cut power cables and rendered layers of safety-backup systems ineffective.

Ukrainian forces likely used “tactical surprise” to advance at least 12 miles into Russian-held territory in the Kharkiv region on Wednesday.

The U.S. and its allies estimate that tens of thousands of Russian troops have been killed or wounded and huge amounts of military equipment destroyed since Putin ordered the Feb. 24 invasion.

Shelling continued around Europe’s largest nuclear plant on Tuesday, a day after it was again knocked off Ukraine’s electrical grid and put in the precarious position of relying on its own power to run its safety systems.

Six of the international agency’s experts remain at the plant, and there will be a ‘permanent presence on site … with two of our experts who will be continuing the work.’

The U.S. government highlighted its finding as Russian President Vladimir Putin last week ordered the Russian military to increase the number of troops by 137,000 to a total of 1.15 million.

A surge in fighting on Ukraine’s southern front is fueling speculation that the long-awaited Ukrainian counteroffensive to try to turn the tide of the war is underway.

To avoid a nuclear disaster, the nuclear watchdog’s chief has sought access for months to the Zaporizhzhia plant, which Russian forces have occupied and Ukrainian workers have operated since the early days of the 6-month-old war.