Ukraine's new army chief said Wednesday the situation on the front line was "extremely difficult" as delays to much-needed US military aid cast a shadow over how long Kyiv's troops can hold out.
The 1,000-kilometre (620-mile) front line has barely moved in more than a year, with Kyiv's forces back on the defensive after last year's failed counter-offensive and military leaders acknowledging Russia has a manpower advantage.
The warning came even as Kyiv said it had destroyed another Russian warship in the Black Sea, the latest in a string of successful attacks on Russia's naval fleet.
"The operational environment is extremely complex and stressful. The Russian occupiers continue to increase their efforts and have a numerical advantage in personnel," commander-in-chief Oleksandr Syrsky said Wednesday.
Syrsky was conducting his first visit to the front line since he replaced the popular Valery Zaluzhny last week in a major military shake-up.
Along with Defence Minister Rustem Umerov, Syrsky had visited troops fighting around Avdiivka, a key flashpoint where Russia is mounting a major attempt to capture the city.
"We are doing everything possible to prevent the enemy from advancing deep into our territory," Syrsky said in a post on social media, saying his troops were operating in "extremely difficult conditions".
Russian military bloggers and local officials have said Ukrainian forces appear to be conserving ammunition as supplies run low.
Ukraine relies on Western -- predominantly US -- support to fund and equip its armed forces with the shells, bullets, rockets, tanks and air defences it needs to hold off Russian attacks.
But the latest multi-billion-dollar aid package has been held up in the US Congress since last year amid political wrangling, threatening to hobble Ukraine's defensive capacity.
The US Senate this week approved $60 billion of funding for Ukraine, but it is unclear whether it will win support in the House of Representatives.
Kyiv has insisted it is holding strong in the face of a renewed Russian offensive, even as doubts linger over the future of Western support.
"Despite the difficult situation, Ukraine's defence forces are inflicting significant losses on the enemy," Syrsky said Wednesday.
One of those losses appeared to come in the Black Sea overnight as Ukraine said it had sunk a Russian warship off the southern coast of Crimea.
Kyiv's military intelligence unit and its armed forces said they had "destroyed" the Caesar Kunikov landing ship in an attack using naval drones.
The strikes inflicted "critical holes on the left side and (the ship) began to sink," the GUR intelligence agency said.
It published footage of what it said was a sea drone approaching the Russian ship before a blast and a large fire can be seen.
There was no comment from Russia's defence ministry, which typically does not respond to Ukrainian claims of successful operations.
But Russian military bloggers with close links to the armed forces said it was likely the ship had been hit by Ukrainian forces.
As the conflict has ground to a stalemate on land, Ukraine has secured success in the Black Sea -- sinking several Russian warships near the annexed peninsula of Crimea and reopening a commercial shipping route for its agricultural exports.
"Time after time the Black Sea fleet has turned out to be incompetent and unable to repel attacks from Ukrainian formations," blasted the Rybar Telegram channel, one of the largest pro-war Russian accounts.
Separately, Ukrainian officials said a Russian rocket strike on a hospital killed at least three people, including a pregnant woman and a child.
The attack, on the eastern town of Selydove, killed a 38-year-old pregnant woman, as well as another woman and her nine-year-old son, Ukraine's general prosecutor said.
Some 12 people, including a six-month-old child, were also injured in the strike.
