Russian forces have seized the city of Kreminna in eastern Ukraine, a sign the "battle for Donbas" has well and truly begun as Russia shifts focus to claim Ukraine's industrial heartlands.
Local officials revealed Ukrainian troops withdrew from the city after Russian forces attacked "from all sides".
However, Ukrainian government officials say they have so far managed to hold the line elsewhere.
What happened in Kreminna?
Kreminna, which had a population of more than 18,000 before the war with Russia, is the first city reported to have been taken by Russian forces since they launched a new offensive in eastern Ukraine.
"Our defenders had to withdraw. They have entrenched themselves in new positions and continue to fight the Russian army."
He did not say when the Russian forces established control over Kreminna but said they had attacked "from all sides".
"It is impossible to calculate the number of dead among the civilian population," Mr Gaidai said.
"We have official statistics — about 200 dead — but in reality there are many more, " he added, without making clear what period the estimated death toll covered.
Sonia Mycak, a research fellow of the Ukrainian Studies Foundation at ANU, told the ABC she did not regard the occupation of Kreminna as decisive, saying it had been expected that Russian forces would now try to occupy other parts of Luhansk oblast.
Dr Mycak also pointed to comments made earlier on Wednesday by Ukrainian military official Serhii Haidai at a press conference facilitated by the Ukraine Media Centre in Kyiv.
She cited Mr Haidai as saying: "Nothing extraordinary occurred in Kreminna, it was a strategic decision to withdraw, regroup and continue to fight elsewhere."
"Ukrainian forces had been defending Kreminna for almost two months. Ukrainian troops have now consolidated their new positions and continue to fight the Russian army, but more effectively".
Earlier, Mr Haidai said street battles had made evacuation of Kreminna impossible.
He said the town came under heavy artillery fire on Monday, setting seven residential buildings on fire, and that the Olympus sports complex, where Ukraine's Olympic team trains, was targeted.
He later said on Ukrainian TV that Russians took control of the city after "levelling everything to the ground," so the Ukrainian forces retreated to regroup.
"It simply makes no sense to stand in one place, to die for everyone, without causing significant damage to the enemy," he said.
Where is Kreminna?
The city of Kreminna is situated 574 kilometres south-east of the capital Kyiv and 100km west of the Russian border, in the Luhansk province, or oblast.
Luhansk and the neighbouring Donetsk province make up the Donbas region, Ukraine's mostly Russian-speaking industrial heartland.
This is also where Moscow-backed separatists have been fighting Ukrainian forces since 2014 and have declared two independent republics that have been recognised by Russia.
How are the Russians doing elsewhere in the east?
An assessment by the US-based Institute for the Study of War said Russia was mounting ground offensives around several cities in eastern Ukraine, but only the advance through Kreminna had made "significant progress".
Russian Defence Ministry spokesman Major General Igor Konashenkov said Moscow's forces bombarded numerous Ukrainian military sites, including troop concentrations and missile-warhead storage depots, in or near several cities or villages.
Those claims could not be independently verified.
Elsewhere, the eastern cities of Kharkiv and Kramatorsk have come under continued attack. Russia also said it struck areas around Zaporizhzhia and Dnipro west of the Donbas with missiles.
Multiple explosions were heard early on Wednesday in the southern city of Mykolaiv, the regional governor said. A hospital was reported to have been shelled earlier in the nearby town of Bashtanka.
In Mariupol, the now-devastated port city in the Donbas, Ukrainian troops said the Russian military dropped heavy bombs to flatten what was left of a sprawling steel plant and hit a hospital where hundreds were staying.
Russia has denied that its troops are deliberately targeting civilians.
What does Kreminna's capture mean for the 'east offensive'?
After failing to capture the capital Kyiv, Russia has switched focus to instead seizing the Donbas region after regrouping along the border.
Ukraine said on Monday that Russian forces had launched a new eastern Ukraine-focused offensive.
Capturing the Donbas and the southern port city of Mariupol would help Russia establish a land link between territory it controls in eastern Ukraine and the Crimea region that Moscow seized and annexed in 2014.
The capture of Kreminna takes Russian forces a step closer to the much larger city of Kramatorsk, one of Russia's potential targets.
The breakthrough in Kreminna could also help the Russians encircle Ukrainian troops in the region by advancing on them from the north and south and squeezing them against territory held by Moscow's troops to the east.
Oleksiy Danilov, secretary of Ukraine’s national security council, said the defensive line had held elsewhere.
The capture of Kreminna also takes the Russians closer to the city of Slovyansk, whose loss by Russia-backed separatists represented a humiliating setback for Moscow in the early stages of the separatist conflict in 2014.
ABC/wires
