Russian forces are seeking to swallow-up the last remaining Ukrainian stronghold in the eastern Luhansk region, the governor said Saturday, while pressing their momentum following the withdrawal of Ukrainian troops from the charred ruins of Sievierodonetsk.

Russia also launched dozens of missiles on several areas across the country far from the heart of the eastern battles. Some of the missiles were fired from Russian long-range Tu-22 bombers deployed to Belarus for the first time, Ukraine's air command said.

The bombardment preceded a meeting between Russian President Vladimir Putin and Belarusian President Alexander Lukashenko, during which Putin announced that Russia planned to send the Iskander-M missile system to Belarus.

Serhiy Haidai, the governor of Luhansk province, said on Facebook that Russian and Moscow-backed separatist fighters were trying to blockade Lysychansk from the south. The city lies just to the west of Sievierodonetsk, which has endured weeks of bombardment and house-to-house fighting.

Capturing Lysychansk would give Russian forces control of every major settlement in the province, making a significant step in Russia’s aim of capturing the entire Donbas region. The Russians and separatists also control about half of Donetsk, the second province in the Donbas.

Russia's Interfax news agency quoted a spokesman for the separatist forces, Andrei Marochko, as saying Russian troops and separatist fighters had entered Lysychansk and that fighting was taking place in the heart of the city. There was no immediate comment on the claim from the Ukrainian side.

Lysychansk and Sievierodonetsk have been the focal point of a Russian offensive aimed at capturing all of the Donbas and destroying the Ukrainian military defending it — the most capable and battle-hardened segment of the country’s armed forces.

Russian bombardment has reduced most of Sievierodonetsk to rubble and cut its population from 100,000 to 10,000. Some Ukrainian troops were holed up in the huge Azot chemical factory on the city’s edge. A separatist representative, Ivan Filiponenko, said forces evacuated 800 civilians from the plant during the night, Interfax reported.

After Haidai said Friday that Ukrainian forces had begun retreating from Sievierodonetsk, military analyst Oleg Zhdanov said some of the troops were heading for Lysychansk. But Russian moves to cut off Lysychansk will give those retreating troops little respite.

Some 1,000 kilometers (600 miles) to the west, four Russian cruise missiles fired from the Black Sea hit a “military object” in Yaroviv, Lviv regional governor Maksym Kozytskyy said. He did not give further details of the target, but Yaroviv has a sizable military base used for training fighters, including foreigners who have volunteered to fight for Ukraine.

Russian missiles struck the Yaroviv base in March, killing 35 people. The Lviv region, although far from the front lines, has come under fire at various points in the the war as Russia's military worked to destroy fuel storage sites.

About 30 Russian missiles were fired on the Zhytomyr region in central Ukraine on Saturday morning, killing one Ukrainian soldier, regional governor Vitaliy Buchenko said.

In the south along the Black Sea, nine missiles fired from Crimea hit the port city of Mykolaiv, the Ukrainian military said.

In the north, about 20 missiles were fired from Belarus into the Chernihiv region, the Ukrainian military said.

The neighboring country hosts Russian military units and was used as a staging ground before Russia invaded Ukraine, but its own troops have not crossed the border.

During his meeting in St. Petersburg with Lukashenko, Putin told him the Iskander-M missile systems would be arriving in the coming months. He noted that they can fire either ballistic or cruise missiles and carry nuclear as well as conventional warheads.

Russia has launched several Iskander missiles into Ukraine during the war.

A senior U.S. defense official, speaking in Washington on condition of anonymity, on Friday called the Ukrainians’ withdrawal from Sievierodonetsk a “tactical retrograde” to consolidate forces into positions where they can better defend themselves. The move will reinforce Ukraine’s efforts to keep Russian forces pinned down in a small area, the official said.

Following a botched attempt to capture Kyiv, Ukraine’s capital, in the early stage of the invasion that started Feb. 24, Russian forces have shifted their focus to the Donbas, where the Ukrainian forces have fought Moscow-backed separatists since 2014.

After repeated Ukrainian requests to its Western allies for heavier weaponry to counter Russia’s edge in firepower, four medium-range American rocket launchers arrived this week, with four more on the way.

The senior U.S. defense official said Friday that more Ukrainian forces are training outside Ukraine to use the High Mobility Artillery Rocket Systems, or HIMARS, and are expected back in their country with the weapons by mid-July. The rockets can travel about 45 miles (70 kilometers). Also to be sent are 18 U.S. coastal and river patrol boats.

The official said there is no evidence Russia has intercepted any of the steady flow of weapons into Ukraine from the U.S. and other nations. Russia has repeatedly threatened to strike, or actually claimed to have hit, such shipments.