Days before non-Orthodox Christmas, Ukrainian President Volodymyr Zelenskyy urged his fellow citizens to maintain their fighting spirit and continue defending the country.

"Maximum attention is needed for defense, maximum effort for the state, maximum energy for Ukraine to achieve its goals," said Zelenskyy in his evening video message broadcast in Kyiv on Thursday.

The time to rest will come later, he said, even as air raid sirens over Kyiv and other Ukrainian cities heralded another night of Russian drone attacks.

According to preliminary information from Kyiv's military administration, debris from a downed drone crashed into a residential building in the southwest part of the city. The administration also published photos of a destroyed flat.

For the first time, Ukraine is officially celebrating Christmas on Dec. 25 this year, adopting the Western model, and no longer only on Jan. 7, in accordance with the Christian Orthodox custom.

"Now, before Christmas, everyone in our state must remember that this is a time to concentrate, a time to work," said Zelenskyy. The fate of the country will be decided in the regions of Kharkiv, Luhansk, Donetsk, Zaporizhzhya and Kherson, which have been attacked by Russia.

Meanwhile, the Kremlin announced that Russian military conscripts are to receive their call-up papers digitally from the autumn of next year.

According to a document published on the Kremlin website, conscripts will then no longer have to appear in person in their district recruitment offices, in accordance with legislation currently in force. In addition, the military will have a new deputy minister post for digitalization issues.

In April, Russian President Vladimir Putin signed a law permitting men to be called up for military service more easily than before. Under its provisions, call-up papers will no longer have to be served in person, and conscripts registered online will no longer be allowed to leave Russia before presenting themselves for service.

A digital conscript register is to be set up as well. Media reports said there had been problems with implementation. The new law has raised concerns of a fresh wave of mobilization to meet the demand for troops on battlefields in Ukraine.

During a marathon question-and-answer session a week ago, Putin said no new mobilization was necessary and that the 300,000 troops called up last autumn were "fighting excellently."

The Ukrainian Ministry of Defense, meanwhile, again appealed to Ukrainian men living abroad to return home and defend their country against the Russian invasion as soldiers.

However, there are no plans to bring men back from abroad and call them up under pressure, said the spokesperson, Illarion Pavlyuk. He sought to clarify statements made by Ukrainian Defense Minister Rustem Umerov about the mobilization of men abroad.

Umerov earlier said in an interview that there are discussions about placing legal "restrictions" on Ukrainian men who remain abroad.

Hundreds of thousands of Ukrainians are registered as war refugees in Germany and other countries. Officially, men between the ages of 18 and 60 who are fit for military service are not allowed to leave the country, although many nonetheless managed to leave.

"The minister is calling on all citizens of Ukraine to join the armed forces wherever they are," said Pavlyuk. "Does this also apply to Ukrainians who are abroad? Without a doubt. Defending the country in times of war is the constitutional duty of all citizens."

But he said that there are no plans to use sanctions or legal pressure on those who remain outside Ukraine.

In fighting that continued in Ukraine on Thursday, at least three people were killed in the Russian bombardment of two coal mines near the city of Toretsk in eastern Ukraine, according to reports from Kyiv.

"Another five were injured," Ukrainian Interior Minister Ihor Klymenko said on Telegram.

Several buildings and equipment were damaged. However, 32 coal miners working underground were able to return to the surface safely.

Toretsk is located in the Donetsk mining region, some 5 kilometers (3.11 miles) from the front line between Ukrainian and Russian troops.

According to Ukrainian authorities, the attack was carried out with four glide bombs.

But Ukrainian air defenses managed to fend off the majority of Russian combat drones in another wave of nighttime attacks overnight.

Of a total of 35 drones, 34 were destroyed on approach, the Ukrainian air force announced on Telegram on Thursday morning. The air defense was active in several regions, including around the capital Kyiv, it said.

Almost two years after the start of the full-scale Russian invasion, Ukraine is currently reporting drone attacks almost every night and is heavily reliant on weapons systems from the West for defense.

This is another reason why Kyiv is very much hoping that the aid from the European Union and the United States, which is currently faltering, will not collapse.