Half of promised Western military support to Ukraine fails to arrive on time, complicating the task of military planners and ultimately costing the lives of soldiers in Russia’s war, the Ukrainian defense minister said Sunday.

Rustan Umerov, speaking at the “Ukraine. Year 2024″ forum in Kyiv, stressed that each delayed aid shipment meant Ukrainian troop losses, and underscored Russia’s superior military might.

Commemorations to mark the second anniversary of Russia’s full-scale invasion of Ukraine on Saturday brought expressions of continued support, new bilateral security agreements and new aid commitments from Ukraine’s Western allies. But Umerov said that they still needed to deliver on their commitments if Ukraine is to have any chance of holding out against Russia.

“We look to the enemy: their economy is almost $2 trillion, they use up to 15% official and nonofficial budget (funds) for the war, which constitutes over $100 billion annually. So basically whenever a commitment doesn’t come on time, we lose people, we lose territory,” he said.

Umerov and the Ukrainian military’s commander-in-chief, Oleksandr Syrskyi, toured front-line combat posts earlier Sunday amid a worsening ammunition shortage and dogged Russian attacks in the east.

They heard from front-line troops and “thoroughly analyzed” the battlefield situation on their visit, Syrskyi said in a Telegram update. He didn’t specify where exactly he and Umerov went, but said that “the situation is difficult” for Ukrainian troops and “needs constant control” along many stretches of the front.

Russian forces on Sunday appeared to be pressing on west of Avdiivka, the strategic city whose capture this month handed Moscow a major victory as fierce fighting rages on in eastern Ukraine.

Gen. Oleksandr Tarnavskyi, who leads Ukrainian forces fighting in the area, said Sunday that his troops had retreated from much of Lastochkyne, a western suburb of Avdiivka. Some Ukrainian media on Saturday reported that Russian troops had taken Lastochkyne, but there was no official confirmation from Kyiv and the battlefield situation appeared fluid.

Earlier this month, Syrskyi replaced Ukraine’s top military commander, Valerii Zaluzhny, in the most significant shake-up of the top brass since the start of the full-scale war, after a long-expected counteroffensive last summer failed to produce major breakthroughs and as military aid for Kyiv hangs in the balance in the U.S. Congress. Russia still controls roughly a quarter of the country.

Speaking at the forum in Kyiv, Umerov insisted on Sunday that Ukrainian forces were doing “everything that’s possible, and also what’s impossible, to secure a breakthrough” this year. The defense minister also said that a “strong” military strategy is already in place for the coming months, but didn’t disclose details.

Russian shelling and rocket strikes on Sunday continued to pummel Ukraine’s south and east, as local Ukrainian officials reported that at least two civilians were killed and eight others were wounded in the Zaporizhzhia and Kherson provinces.

A woman was wounded and a railway station turned into a smoldering ruin amid heavy shelling in the eastern city of Kostiantynivka, according to the head of the municipal military administration. Ukraine’s public broadcaster, Suspilne, cited local police as saying that the strikes also damaged an Orthodox church, more than a dozen residential buildings and dozens of shops, a post office, schools and local government offices.

Russia and Ukraine also continued to trade nightly drone attacks, with Ukraine’s air defenses shooting down 16 of 18 Iranian-made Shahed drones launched overnight by Moscow. A Russian drone on Sunday morning struck an unspecified facility in Ukraine’s western Khmelnytskyi region, the regional military administration reported without giving details.

Meanwhile, Russia’s defense ministry on Sunday morning reported it had downed seven Ukrainian drones — four over the Black Sea and three over Russia’s southern Belgorod region. It didn’t immediately mention any casualties or damage.