Kyiv, Ukraine — While Ukrainian forces are in Russia’s western Kursk region, they are encountering a new enemy, North Korea’s elite soldiers.

On Sunday, Ukrainian infantry and armoured vehicles resumed an offensive in three directions in Kursk, trying to fence their toehold in the district centre of Sudzha that they had seized in August.

On Tuesday, they occupied at least 3 villages northeast of Sudzha and inflicted casualties on North Koreans fighting in the separate Russian command.

“We have clarified their ranks: they have losses, Kim has not only sent ordinary soldiers,” a Ukrainian soldier told Al Jazeera, referring to North Korean leader Kim Jong Un.

He did not disclose his name, details and exact whereabouts of the battles in accordance with wartime regulations.

South Korean and US officials have said Kim deployed more than 10,000 elite soldiers to Kursk. Hundreds are understood to have been killed there already.

More than 450km (280 miles) south of Kursk, another Ukrainian serviceman keeps repelling waves of Russian infantrymen near the key southeastern city of Pokrovsk.

“It seems that they send a new brigade every day,” the military told Al Jazeera.

The Russians continue to move ahead in spite of a lack of tanks and armored vehicles.

“They continue to press. The only challenge they have is their team, they release it as they did 3 or 4 months ago,” he said.

But the greatest challenge that his unity, like all the armed forces of Ukraine, faces a disastrous shortage of labor.

Last week, Ukrainian troops withdrew from the eastern city of Kurakhove, which Russian troops claimed on Monday.

kyiv’s forces have also lost a key coal mine near Pokrovsk and could be about to lose the largest lithium tank in Ukraine, in Shevchenkove.

“Kurakhove’s defense comforts were taken just because we had no one there,” said the soldier. “Maximum motivated infantry men have been killed, the new ones lack and motivation. “

He also cited poor decisions made by commanding officers, alleging they want to appease their superiors and do not value the lives of servicemen.

“I’ve been wounded so many times because of the commanders’ stupidity,” he said.

The Russian forces that seized Kurakhove looted deserted apartments, alleged a woman.

“They are heading to apartments that have broken through the bombing, they fly everything they can remove,” said Olena Basenko, a former Kurakhove sales employee who is looking for her old aunt who refused to leave the city, she told Al Jazeera

“Some ‘liberators’ they are,” she said sarcastically referring to Moscow’s pledge to “liberate” Ukraine from President Volodymyr Zelenskyy’s “neo-Nazi junta” – Russian claims that have been debunked throughout the war.

Ukraine’s shortage of manpower has led some analysts to doubt Kyiv’s push to resume the Kursk offensive.

“Zelenskyy’s strategy is to amass brigades with apparatus in the back to solemnly lose them in the country of Kursk to gain 1. 5 km [1 mile] of farmland,” Nikolay Mitrokhin, a researcher at Germany’s University of Bremen, told Al Jazeera.

The sets that advance in Kursk may have used to protect Kurakhove, he said.

However, others see Kursk’s offensive as a possibility to ensure a vital negotiation problem.

Ukraine can visit a Russian nuclear force plant in the city of Kurchatov, which is about 70 km (45 miles) northeast of Southzha and can see to capture the regional capital of Kursk 30 km (20 miles) further.

If you succeed, Kurchatov’s acquisition can a vital strategic gain, according to the former attached leader of the general personnel of the Ukrainian Armed Forces.

“We don’t want to get worse, but we want it,” said Lieutenant General Ihor Romanenko to Al Jazeera.

Kyiv may also invade Russia’s neighboring Bryansk region, a blow to Russian President Vladimir Putin’s domestic reputation, he said.

“It will be painful in Putin, and if there is an offensive somewhere in Bryansk or in regions, it will make you think,” Romanenko said.

Some Russians ridicule Putin who have led to the first foreign invasion of Western Russia since World War II.

“If the grandfather in the bunker is so wise, why do we have Ukrainians on Russian soil?Something is wrong,” Roman, a 48-year-old Muscovite who served in a tank unit in the 1990s, Al Jazeera, taunting the Russian president.

Bryansk borders Ukraine and has been attacked through two sets of the Ukrainian army formed by Pro-Ukrainian Russian combatants.

Romanenko said that Putin’s resolution on Russia’s offensive in southeast Ukraine means a “Fiasco” of Trump’s “peace plan”.

“This ended with a fiasco because Putin rejected the proposed edition through the Trump team,” he said.

Trump has offered few details of the plan, but, according to his team, it may include the establishment of a “demilitarised zone” along the current front line, Kyiv’s ceding of Russia-occupied areas and a delay of Ukraine’s NATO membership.

At the end of last year, Ukraine scored a small victory that may herald huge losses in Russian navy bases and civilian seaports.

On December 31, Ukrainian sea drones, or un-piloted vessels armed with small missiles, attacked Russian helicopters in the bay of Sevastopol, the main naval base in annexed Crimea.

Ukraine claimed to have shot down two helicopters, killing all 16 crew members.

Moscow acknowledged no losses but said its forces destroyed four Ukrainian unmanned aircraft and two sea drones.

The attack showed that sea drones could wreak havoc on Russian port and naval infrastructure along the Black Sea, Bremen University’s Mitrokhin said.

Furthermore, Kyiv could use sea drones for attacks on the Russian navy in the Baltic, Barents and White Seas and in the Pacific.

“There is so much infrastructure there that it will be hard to cover it even with boom barriers, let alone protect them from all sides like in Sevastopol or [the Crimean port of] Feodosiya,” he said.

Meanwhile, the ongoing war of attrition tests Ukraine and Russia’s economies.

The Russian economy has “partially adapted to the pressure from [Western] sanctions, but it currently enters the inflation shock of overheating and slower growth” because of the Central Bank’s high percentage rates, Kyiv-based analyst Aleksey Kusch said.

The Ukrainian economy is “in shock” because of severely damaged energy infrastructure and a lack of labour force, he said.

But hydrocarbon exports help Russia’s economy recover from the shock, while Ukraine is kept afloat by Western financial aid.

“This creates a sure effect of parity in the midst of war resistance,” Kushch told Al Jazeera.