The Russian military has not yet won full control of Kherson, the Pentagon said on Thursday, a day after Moscow claimed to have taken over the southern Ukrainian city.
The Russian army claimed on Wednesday that it had full control of the provincial capital of about 250,000 people, with Russian forces occupying the regional administration building.
But a US defence official told Pentagon reporters it was too soon to say who was in control.
“There's still fighting there, so we're not ready to call it one way or another,” the US official said. The official added that the situation on the ground was changing quickly.
If Kherson were to be captured, it would be the first significant urban centre to fall into the hands of Russian troops.
The official said Russian forces may want to use Kherson as a springboard to attack city of Mykolaiv, about 60 kilometres to the north-west.
From there, they might go after Odesa, “not just from the sea, but from the ground”, the official said.
The official said a large Russian convoy of hundreds of tanks and other vehicles still appeared to be stalled about 25km from Kyiv and had made no real progress in days.
The convoy, which earlier in the week had seemed poised to launch an assault on the capital, has been plagued by fuel and food shortages, the Pentagon says.
British Defence Secretary Ben Wallace earlier on Thursday said Russian President Vladimir Putin had deployed thermobaric weapons systems in Ukraine.
Such weapons, sometimes called vacuum bombs, cause a powerful shock wave that sucks oxygen from the air — causing horrific asphyxiation for anyone within its target zone.
The US official said: “We know that they have the launching systems available to them in Ukraine that could be used for rockets that have a thermobaric warhead on them. But we cannot confirm that those weapons are in Ukraine and we cannot confirm any examples of use.”
The official said that Russia had moved about 90 per cent of its pre-staged combat power into Ukraine so far and about 480 missiles had been fired by Russian forces at Ukrainian targets.
Ukrainian officials said their missile-defence systems have parried numerous attacks, though some missiles have clearly made it through.
Kyiv Mayor Vitali Klitschko said explosions heard overnight in the capital were Russian missiles being shot down.
Agencies contributed to this report
