"The Russians are using mean tactics. We are losing"

The text explains that the command of the Ukrainian army has also sent members of the Ukrainian National Guard to the Kharkiv region, where fierce fighting is taking place because the Russian forces are advancing unstoppably.

The members of that unit practically went from a fierce battle in the east to another one in the north, without rest.

"The situation is tense and it is difficult to predict how it will develop," soldier Andriy told the BBC.

"The Russians want to withdraw our forces from the defensive lines in the Donetsk and Lugansk regions. It was only a matter of time. The Russians always use sneaky tactics," he says.

Another soldier, Victor, who lost his fingers in a mortar blast, says they fought off a wave of attacks.

"There are a lot of them. The Russians have everything, whatever they want," says Viktor, "and we have nothing to fight with. But we do what we can," he adds.

Delays in US military support have hampered Ukraine's defense. It was necessary to rationalize the use of ammunition for several months already, so that Russia fired 10 times more artillery shells on average.

At the position, hidden in a line of trees outside Vovchansk, members of the Ukrainian 57th Brigade fire 50 to 100 shells a day to defend the city.

This unit also fought further east before the call for the defense of Kharkiv arrived. Another nearby brigade arrived from Robotin in the south, where Russian forces are also advancing.

Mykhailo, the Ukrainian artillery commander, says: "We are losing Vovchansk, and we are also losing the villages around Vovchansk."