KYIV: Ukraine's new army chief said on Wednesday the situation on the front line was "extremely difficult" as delays to much-needed United States military aid cast a shadow over how long Kyiv's troops can hold out.

The 1,000-kilometer (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 counteroffensive and military leaders acknowledging that 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 Moscow'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 Col. Gen. Oleksandr Syrskyi said on Wednesday.

Syrskyi was conducting his first visit to the front line since he replaced the popular Valery Zaluzhny last week in a major military shakeup.

Along with Defense Minister Rustem Umerov, Syrskyi 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," Syrskyi said in a social media post, adding that 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 American — support to fund and equip its armed forces with the shells, bullets, rockets, tanks and air defenses it needs to hold off Russian attacks.

But the latest multibillion-dollar aid package has been held up in the United States Congress since last year amid political wrangling, threatening to hobble Ukraine's defensive capacity.

The US Senate this week approved $60 billion in funding for Ukraine, but it is unclear whether it would win support in the House of Representatives.

Ship hit

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 defense forces are inflicting significant losses on the enemy," Syrskyi said on 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 the Moscow-annexed Crimea Peninsula.

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 Defense Intelligence of Ukraine said.

It published footage of what it said was a sea drone approaching the Russian ship before a blast and a large fire could be seen.

There was no comment from Russia's Defense 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 Kyiv's forces had struck the ship.

As the conflict has ground to a stalemate on land, Ukraine has secured success in the Black Sea, sinking several Russian warships near 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.