Russian move on Kyiv stalled with some signs of low morale in troops, says US official

Russia's military move on Kyiv has stalled as its forces struggle with basic logistics challenges, including shortages of food and fuel, with some units appearing to be gripped by low morale, a senior US defence official said on Tuesday.

Russia warned residents in capital Kyiv to flee their homes on Tuesday and rained rockets down on the second city of Kharkiv, as Russian commanders who have failed to achieve a quick victory shifted their tactics to intensify the bombardment of Ukrainian cities.

Satellite images taken on Monday show a Russian military convoy north of Kyiv that stretches for about 40 miles (64 km), substantially longer than the 17 miles (27 km) reported earlier in the day.

"One reason why things appear to be stalled north of Kyiv is that the Russians themselves are regrouping and rethinking and trying to adjust to the challenges that they've had," said the official, speaking on condition of anonymity.

The official told reporters that it was unclear whether the convoy itself had stalled, but it was not making much progress.

"The Russians have been surprised by some of the morale problems that they're experiencing and I think they're none too pleased about the logistics and sustainment challenges they've had," the official said, without providing evidence.

Images have appeared on social media over the past several days showing Russian tanks and military vehicles idled on the side of roads, some appearing to have run out of fuel.

The official said the United States had seen indications of some Russian units surrendering without a fight, but did not provide details on how many troops that included.

Still, the bombardment continues. Russian forces attacked a television tower in Kyiv, potentially disrupting its signal, Ukrainian Interior Ministry adviser Anton Herashchenko said on Tuesday.

The Russian defence ministry also said Russia would strike sites in Kyiv belonging to Ukraine's security service and a special operations unit.

"The Russian defence ministry threatening statement today... is indicative of a change here, that they are being quite open about," the official said.

Rocket strikes on Kharkiv killed at least 10 people and wounded 35, Herashchenko said.

Human rights groups and Ukraine's ambassador to the United States on Monday accused Russia of attacking Ukrainians with cluster bombs and vacuum bombs, weapons that have been condemned by a variety of international organisations.

The US official said that Russia had systems that could launch vacuum bombs, but could not confirm that they had been used in Ukraine.

Munitions experts told reporters after reviewing footage that it appeared to show multiple cluster bombs being fired on Kharkiv.

As the invasion entered its sixth day, Russia had committed about 80% of its pre-staged combat into Ukraine and launched more than 400 missiles on Ukrainian targets, but did not control any major cities or have complete control of the skies over Ukraine.