What you need to know
The UK's Ministry of Defense says Russian forces have made modest gains near the town of Avdiivka in the eastern Ukrainian region of Donbas.
Moscow's forces are advancing slowly, the ministry's report says, with heavy fighting ongoing near the Avdiivka Coke Plant to the northwest of the town.
The British assessment says Russia's recent gains there, the biggest in months, have cost it a large number of casualties.
In other Ukraine-related news, NATO Secretary General Jens Stoltenberg has said he expects Western support for Kyiv will continue despite some pushback in the US and EU.
Here's a look at the latest developments in Russia's war in Ukraine on Tuesday, November 28:
Finland to close last border crossing with Russia
Finland's prime minister anounced the closing of the country's last border crossing with Russia. The move follows an influx of migrants which Helsinki claims was a hybrid attack orchestrated by Moscow.
Interior Minister Mari Rantanen said the closure would come into effect overnight between Wednesday and Thursday and last until December 13.
"Finland is the target of a Russian hybrid operation. This is a matter of national security," Rantanen said.
The Nordic country shares a 1,340-kilometre (830-mile) border with Russia. Since the beginning of August, nearly 1,000 migrants have entered Finland without a visa through the eastern border crossing points.
Russian Deputy Foreign Minister Alexander Grushko criticized Finland's decision to close the border as "simply irrational", according to Russian media outlets.
Finland's relations with Russia has soured considerably after the invasion of Ukraine, which prompted it to join the US-led military alliance NATO in April, reversing its decades-long policy of military non-alignment.
Ukraine spy chief's wife poisoned, reports say
Ukrainian media outlets are reporting that Marianna Budanova, the wife of the country's intelligence chief, has been poisoned with heavy metals.
If confirmed as deliberate, the alleged poisoning would be the most serious targeting of a top Ukrainian leadership figure's family member since Russia launched the war in February last year.
Budanova is the wife of Kyrylo Budanov, who leads Ukraine's GUR military intelligence agency. The GUR has been prominently involved in secret operations against Moscow's forces during the 21-month war.
Budanov enjoys a high public profile in Ukraine, where he is portrayed as a mastermind of Kyiv's efforts to strike back at Russia.
Reports did not suggest who was behind the alleged poisoning or clarify when it took place.
The media outlet Babel cited an unnamed source as saying Budanova had been in a hospital where she had been treated for the effects of the poisoning.
NATO chief confident of US support for Ukraine
NATO Secretary-General Jens Stoltenberg says he is "confident" that the United States will keep up weapons deliveries to Ukraine.
His comments come despite opposition in Washington from hardline Republicans throwing into question the future of US assistance.
The US has provided over $40 billion (more than €36 billion) in security aid to Ukraine since Russia launched its full-scale invasion in February 2022, and the White House has pledged to back Kyiv for as long as necessary.
"I'm confident that the United States will continue to provide support because it is in the security interest of the United States to do so and it's also in line with what we have agreed," Stoltenberg said at a meeting of NATO foreign ministers.
There are mounting concerns about the future of Western backing for Ukraine, with Kyiv's top general admitting that the fierce fighting has ground to a "stalemate."
The European Union is also struggling to agree on a plan on its own long-term support for arming Ukraine amid opposition from Hungary.
"I urge allies and allies are also committed to continue to deliver support," Stoltenberg said, highlighting some €10 billion pledged recently by Germany and the Netherlands.
Russia edges closer to Donbas coking plant
Russian forces have made some small advances in eastern Ukraine that brought them closer to the coking and chemical plant, the UK Ministry of Defense says.
In its daily report, the ministry says Russian forces edged further forward on the northern axis of a pincer movement in their effort to surround the Donbas town of Avdiivka.
The ministry says Moscow's troops have moved the frontline forward up to 2 kilometers (about 1.25 miles) in the area since the start of October.
"Although modest, this advance likely represents one of the greatest Russian gains since spring 2023," said the report. "It has cost the units involved thousands of casualties."
"This operation is gradually bringing Russian troops closer to the Avdiivka coke and chemical plant, where Ukrainian forces maintain one of their main defensive positions," it added.
The ministry said that although the Russians have forced a bulge in the Ukrainian front line, Kyiv remains in control of a corridor of territory approximately 7 kilometers wide, through which it continues to supply the town.
Correction, December 1, 2023: A previous version of this article stated that the coking plant was located in the northeast of Avdiivka. It is located in the northwest. This has now been corrected. We apologize for the error.
rc/fb (AFP, AP, dpa, Reuters)