Here are five key developments on Friday from Russia's war in Ukraine.
1. Russian forces 'partially surrounded' in Lyman
A senior Russian-backed official has acknowledged that Moscow's forces are "half encircled" in a strategic city in eastern Ukraine.
"At the moment, Lyman is partially surrounded," said Denis Pushilin, the Russian-installed governor in the Donetsk region.
"The Svatove road is under our control, but under fire periodically," he wrote on Telegram, admitting that the nearby villages of Yampil and Drobycheve "are not under total control".
The Ukrainian army was "trying at all costs to spoil our historic events", Pushilin added, referring to the annexation ceremony in Moscow.
A Ukrainian presidential adviser said on Friday that Russia would have to appeal to Kyiv to allow Moscow's encircled troops out.
"Only if, of course, those in Kremlin are concerned with their soldiers," Mykhailo Podolyak added on Twitter.
Lyman is located around 160 kilometres southeast of Kharkiv, Ukraine’s second-largest city. For months, it has served as a logistics and transport hub anchoring Russian operations in the Donetsk region.
The Institute for the Study of War says that losing the city would be a major blow to Moscow's war effort amid annexation plans.
“The collapse of the Lyman pocket will likely be highly consequential to the Russian grouping [and] may allow Ukrainian troops to threaten Russian positions along the western Luhansk,” the Washington-based institute said.
If Kyiv recaptures Lyman, it would be their biggest successful counteroffensive since taking swathes of the Kharkiv region earlier this month.
Russian President Vladimir Putin has made it a priority for Russian forces to control all of the industrial Donbas regions and his "partial mobilisation" of Russian troops aims to fortify Russian positions.
In addition to Lyman, Russian occupation forces in the neighbouring Kherson region reported on Friday that a senior government official was killed in a Ukrainian strike.
Alexei Katerinitshev, a deputy head of the Moscow-backed administration, was killed "in a precise strike" on his home on Thursday night, according to the Russian news agency TASS.
Meanwhile, Ukrainian forces have secured all of the northeastern city of Kupiansk and have driven Russian troops from their remaining positions on the east bank of the Oskil river.
2. Zaporizhzhia missile attack on convoy
Earlier on Friday, at least 23 people died after an air strike on a civilian convoy in the southern Ukrainian region of Zaporizhzhia.
Ukrainian and Russian forces have blamed each other for the attack, which occurred near a crossing point between Ukrainian-controlled territory and the region occupied by Russian forces.
"The enemy launched a rocket attack on a humanitarian convoy of civilians, people were lining up to go to the temporarily occupied area, to meet relatives, to receive aid," Ukrainian regional governor Oleksandr Staroukh said on Telegram.
At least 28 others are reported to have been injured in the air strike. Images shared on social media showed burned-out vehicles and bodies lying in the road.
Zelenskyy lashed out at Russia on Friday, calling its leaders "terrorists" and "bloodthirsty scum" after the missile attack.
"Only complete terrorists can do this and they should have no place in the civilised world," Zelensky said on Telegram.
Ukrainian officials in the Zaporizhzhia region have declared October 1 as a day of mourning for the civilians who were killed in the attack.
The European Union's foreign policy chief Josep Borrell has condemned the "appalling" attack on Zaporizhzhia "in the strongest terms".
"Another heinous attack by Russia on civilians: this time a humanitarian convoy bringing vital help to people living in non-government controlled areas," Borrell wrote on Twitter.
"The EU condemns this appalling attack in the strongest possible terms, those responsible will be held accountable."
Vladimir Rogov, a Russian-installed representative, meanwhile accused Ukrainian forces of firing on the convoy to prevent these civilians from reaching the Russian-occupied area.
Moscow has always denied deliberately attacking civilians.
Russian forces currently control the majority of the Zaporizhzhia region, including Europe's biggest nuclear power plant there - but not the regional capital.
In a separate incident, one person was killed and five injured in overnight Russian strikes on the central city of Dnipro, local officials said. Russian missile strikes also damaged a high-rise building in Mykolaiv and wounded eight people.
3. Putin annexes four occupied Ukrainian regions
Vladimir Putin has formally annexed four regions of eastern Ukraine -- Donetsk, Kherson, Luhansk, and Zaporizhzhia -- that all held so-called "referendums" on joining Russia in the last week.
According to Russian officials, the four regions -- which represent about 15% of Ukraine -- voted overwhelming to be incorporated into Russian territory.
Kyiv and its international allies have slammed them as a sham, with videos on social media showing armed soldiers enforcing the vote door-to-door.
Putin formally signed a decree endorsing the annexation at a ceremony in Moscow's Red Square.
In an earlier speech, the Russian President announced; "there are four new regions of Russia".
"I want the Kyiv government and their sponsors in the West to hear me ... Residents of Donetsk, Luhansk, Zaporizhzhia, and Kherson are becoming our citizens forever."
US President Joe Biden vowed on Thursday to "never, ever, ever" recognise the results of the "Russian-orchestrated" referendums.
"The so-called referendums were a travesty, an absolute travesty," he said, praising the "sacrifice" of Ukrainians to "save their people and maintain the independence of their country.
UN Secretary-General Antonio Guterres also told reporters on Thursday that Russia’s annexation would violate the UN Charter and has “no legal value".
He described the move as “a dangerous escalation” and said it “must not be accepted.”
“Any decision by Russia to go forward will further jeopardize the prospects for peace,” Guterres said.
In response to the planned annexation, Zelenskyy called an emergency meeting of his National Security and Defense Council on Friday.
Kyiv has repeated its vows to recapture the four regions, as well as Crimea, which was similarly annexed in 2014.
For its part, Russia has pledged to defend all its territory — including the newly annexed regions — by all available means, including nuclear weapons.
4. Blame game continues into Nord Stream leaks
The Kremlin has called for a thorough international investigation into leaks along the Nord Stream undersea gas pipelines.
Putin said on Thursday that the "unprecedented sabotage" against pipelines was "an act of international terrorism".
Four days after the leaks were first spotted, it remains unclear who might be behind any attack on the pipelines.
In a joint letter to the UN Security Council, Denmark and Sweden said the damage was caused by "at least two detonations" with "several hundred kilos" of explosives.
According to state media, the head of Russia's foreign intelligence service said that Moscow had materials which indicated the West had a role in the leaks. Moscow has previously said the pipeline damage occurred in territory that is "fully under the control" of US intelligence agencies.
The White House has dismissed Russian allegations that it was responsible.
US Defense Secretary Lloyd Austin has said it is still too soon to speculate who might have been behind the Nord Stream pipeline ruptures.
"Until a complete investigation is done, no one will be able to really determine for certain what happened," Austin told a news conference on Thursday.
The European Union is also investigating the incident and has promised a "robust" response to any intentional disruption of its energy infrastructure.
EU leaders are set to discuss the ramifications of the Nord Stream links at next week's summit in Prague.
Nord Stream AG said it expects the gas leak into the Baltic Sea to stop by Monday, but that it has not been able to access the area to assess the damage.
Ships have been warned to maintain a distance of at least five nautical miles (10 kilometres) from the leaks.
5. Finland formally closes borders to Russian tourist visas
Finland has formally closed its borders to Russian tourists, significantly reducing passenger traffic into the European Union.
From midnight on Friday, Russian citizens can only cross the Finnish border for family visits or for purposes of work or study.
Finland’s 1,300-kilometre land border had been the last direct route for thousands of Russians to cross into the EU.
The bloc has banned all flights from Russia, leaving only rail and road transport links available, and this month agreed to limit issuing free-travel Schengen zone visas.
The Finnish government said the move would lead to a significant drop in cross-border traffic after almost 17,000 Russians crossed the frontier the weekend -- an 80% rise from a week earlier.
The government justified its decision by citing security concerns following “illegal” referendums arranged by Russia in Ukraine and recent leaks in the Nord Stream pipelines.
The European Union’s Migration Commissioner Ylva Johansson has urged the 27 member countries to clamp down on issuing visas to Russian citizens following the annexation of four Ukrainian regions on Friday.
Norway’s Justice Minister says the country may also impose a ban on Russian tourists.
"We will close the border quickly if necessary, and changes can come at short notice," Emilie Enger Mehl said in a statement.
There have been few arrivals in Norway compared to Finland, and the situation is different here,” she added.
Norway is a member of the passport-free Schengen zone despite not being part of the EU.
Last week, President Putin announced the country’s first “partial military mobilization” since World War II.
Thousands of Russians have since fled the country to avoid conscription into the war in Ukraine.
To stem the exodus and intercept military-age citizens, Russian authorities have set up military enlistment offices near the borders with Kazakhstan and Georgia.
Finnish border guards said Russian military personnel have also been stationed at the Torfyanka checkpoint in recent days.
Russia’s Defense Ministry has promised to only draft 300,000 people who have combat or service experience, but multiple media reports say inexperienced citizens are being called up to fight.
On Thursday, Putin said that Russian men mistakenly called up for service should be sent back home and that only reservists with proper training and specialities should be summoned to serve.
The British military says newly mobilised Russian troops coming into Ukraine are equipped with poor medical supplies and knowledge.