KRAMATORSK, Ukraine (AP) — Russia asserted Saturday that its troops and separatist fighters had captured a key railway junction in eastern Ukraine, the second small city to fall to Moscow’s forces this week as they fought to seize all of the country’s contested Donbas region.

Russian Defense Ministry spokesman Igor Konashenkov said the city of Lyman had been “completely liberated” by a joint force of Russian soldiers and the Kremlin-backed separatists, who have waged war in the eastern region bordering Russia for eight years.

Lyman, which had a population of about 20,000 before Russia invaded Ukraine on Feb. 24, serves as a regional railway hub. Ukraine’s train system has ferried arms and evacuated citizens during the war, and it wasn’t immediately clear how the development might affect either capability.

READ MORE: Russia squeezes Ukrainian strongholds in eastern Donbas region

Controlling the city would give the Russian military a foothold for advancing on larger Ukrainian-held cities in Donetsk and Luhansk, the two provinces that make up the Donbas. Since failing to occupy Kyiv, Ukraine’s capital, Russia has concentrated on seizing the last parts of the region not controlled by the separatists.

“If Russia did succeed in taking over these areas, it would highly likely be seen by the Kremlin as a substantive political achievement and be portrayed to the Russian people as justifying the invasion,” the British Ministry of Defense said in a Saturday assessment.

Fighting continued Saturday around Sievierodonetsk and nearby Lysychansk, twin cites that are last major areas under Ukrainian control in Luhansk province. Ukrainian President Volodymyr Zelenskyy reiterated that the situation in the east was “difficult” but expressed confidence his country would prevail with help from Western weapons and sanctions.

“If the occupiers think that Lyman or Sievierodonetsk will be theirs, they are wrong. Donbas will be Ukrainian,” he said.

On Tuesday, Russian troops took over Svitlodarsk, a small municipality south of Sievierodonetsk that hosts a thermal power station, while intensifying efforts to encircle and capture the larger city.

The governor of Luhansk had warned that Ukrainian soldiers might have to retreat from Sievierodonetsk to avoid being surrounded, but he said Saturday that they had repelled an attack.

“We managed to push back the Russians to their previous positions,” Gov. Serhii Haidai said. “However, they do not abandon their attempts to encircle our troops and disrupt logistics in the Luhansk region.”

The advance of Russian forces raised fears that residents would experience the same horrors as people in the southeastern port city Mariupol in the weeks before it fell.

READ MORE: Zelenskyy says Russia must withdraw to pre-war positions before diplomatic talks

Sievierodonetsk’s mayor, Oleksandr Striuk, said Friday that some 1,500 civilians have died there during the war, including from a lack of medicine or because of diseases that could not be treated while the city was under siege.

Before the war, Sievierodonetsk was home to around 100,000 people. About 12,000 to 13,000 remain in the city, where 90% of the buildings are damaged, the mayor told The Associated Press.

Just south of Sievierodonetsk, volunteers worked to evacuate people Friday amid a threatening soundtrack of air raid sirens and booming artillery. AP reporters saw elderly and ill civilians bundled into soft stretchers and slowly carried down apartment building stairs in Bakhmut, a city in northeast Donetsk province.

Svetlana Lvova, the manager of two buildings in Bakhmut, tried to convince reluctant residents to leave but said she and her husband would not evacuate until their son, who was in Sieverodonetsk, returned home.

“I have to know he is alive. That’s why I’m staying here,” Lvova, 66, said.

A nearly three-month siege of Mariupol ended last week when Russia claimed the city’s complete. The city became a symbol of mass destruction and human suffering, as well as of Ukrainian determination to defend the country. More than 20,000 of its civilians are feared dead.

Mariupol’s port reportedly resumed operations after Russian forces finished clearing mines in the Azov Sea off the once-vibrant city. Russian state news agency Tass reported that a vessel bound for the southern Russian city of Rostov-on-Don entered Mariupol’s seaport early Saturday.

Meanwhile, the Ukrainian navy said Saturday morning that Russian ships “continue to block civilian navigation in the waters of the Black and Azov seas” along Ukraine’s southern coast, “making them a zone of hostilities.”

The war in Ukraine has caused global food shortages because the country is a major exporter of grain and other commodities. Moscow and Kyiv have traded blame over which is responsible for keeping shipments tied up, with Russia saying Ukrainian sea mines prevented safe passage.

READ MORE: Russia says it will pay foreign debt in rubles after ban from U.S. banks

The press service of the Ukrainian Naval Forces said in a Facebook post that two Russian missile carriers “capable of carrying up to 16 missiles” were ready for action in the Black Sea. It said that only shipping routes which had been established through multilateral treaties could be considered safe.

Ukrainian officials pressed Western nations for more sophisticated and powerful weapons, especially multiple launch rocket systems. The U.S. Defense Department would not confirm a Friday CNN report saying the Biden administration was preparing to send long-range rocket systems to Ukraine.

Russia’s U.S. ambassador on Saturday branded such a move as “unacceptable” called on the Biden administration to “abandon statements about the military victory of Ukraine.”

A Telegram post published on the Russian embassy’s official channel cited Anatoliy Antonov, Moscow’s top diplomat in Washington, as saying that “the unprecedented pumping of weapons into Ukraine significantly increases the risks of an escalation of the conflict.”

In Russia on Saturday, President Vladimir Putin signed into law a bill that raises the age limits for Russian army contracts. Contractors can now first enter service until age 50 and work until they reach legal retirement age, which is 65 for men and 60 for women.

Previously, Russian law set an age limit of 40 for Russians and 30 for foreigners to sign an initial contract.

Russia’s Defense Ministry said the Russian navy successfully launched a new hypersonic missile from the Barents Sea. The ministry said the recently developed Zircon hypersonic cruise missile had struck its target about 1,000 kilometers away.

If confirmed, the launch could spell trouble for NATO voyages in the Arctic and North Atlantic. Zircon,, described as the world’s fastest non-ballistic missile, can be armed with either a conventional or a nuclear warhead, and is said to be impossible to stop with current anti-missile defense systems.

Moscow’s claims, which could not be immediately verified, came a week after Defense Minister Sergey Shoigu announced that Russia would form new military units in the west of the country in response to Sweden and Finland’s bids to join NATO.

Putin marked the annual Border Guards Day by congratulating the members of the Russian service.

“The tasks you are facing are particularly important now, given the unprecedented political, economic and information pressure on our country and the buildup of NATO military capacity right at Russia’s borders,” Putin said.

Karmanau reported from Lviv, Ukraine. Andrea Rosa in Kharkiv, Ukraine, Andrew Katell in New York and AP journalists around the world contributed.

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