The final fall of Lugansk on the horizon; A new phase of the war begins?

This prompted Ukrainian officials to announce the possibility of withdrawing Ukrainian defenders from Luhansk so that they would not be trapped in a hostile environment.
Lugansk Governor Serhiy Haidai said today that Russian forces had entered Sievierodonetsk - a city of about 100.000 inhabitants that is of great strategic importance to Ukrainian defenders east of it.
Today, there are only about 13.000 people left in the city, and it is estimated that about 1.500 people have died so far. The fall of Sievierodonetsk would cut off Ukrainian forces buried in defensive positions behind Luhansk, which is still under their control.
According to the Washington ISW Research Center, Russian troops launched a direct attack on Sievierodonetsk without the army being able to completely surround the city, which means that its defenders still have supply lines in the west.

Necessary withdrawal Tanjug/AP Photo/Francisco Seco

Russian scouts and special forces tried to occupy the Mir Hotel and its surroundings in the northeastern part of the city. ISW notes that the Russian army has so far had serious problems in conquering urban areas and predicts that the same scenario will be repeated in this case.
"We will have enough strength and resources to defend ourselves," Haidai said in a telegram. "But we may have to withdraw so as not to end up surrounded. Governor of Luhansk also said that as much as 90 percent of the buildings in Sievierodonetsk were damaged and that as many as 14 skyscrapers were destroyed in the last shelling."
According to today's report by the British Ministry of Defense, Russian forces have most likely occupied most of the Liman, a strategically important railway hub in Donetsk, which provides access to important...