Russian forces have also increased attacks on the key frontline city of Avdiivka in eastern Ukraine in an attempt to gain ground, Ukrainian military officials said Sunday.

Ukraine's General Staff said that Russian troops were also continuing their weekslong push to encircle Avdiivka, a Ukrainian stronghold south of Bakhmut and a key target since the beginning of the war. It's considered the gateway to parts of the eastern Donetsk region under Kyiv's control. The General Staff said Russia's air force was playing a key part in the latest assault.

Gen. Oleksandr Tarnavskyi, who leads Ukrainian troops fighting in and near Avdiivka, said Sunday that the attacking Russian forces were ramping up airstrikes, particularly those using guided bombs. He wrote on Telegram that Russian troops had launched 30 airstrikes and 712 artillery barrages at the city and surrounding areas over the previous day, and clashed almost 50 times with Ukrainian units.

President Volodymyr Zelensky warned Ukrainians on Sunday to prepare for new waves of Russian attacks on infrastructure as winter approached and said troops were anticipating an onslaught in the eastern theatre of the war.

A military spokesman said Russian attacks on the shattered eastern town of Avdiivka had eased in the past day, but were likely to intensify in the coming days.

And Ukrainian military intelligence said an explosion killed at least three Russian servicemen in the Russian-occupied southern town of Melitopol, which it described as an “act of revenge” by resistance groups.

Zelenskiy issued his warning during his nightly video address a day after Russian forces carried out their first missile attack on the capital, Kyiv in some seven weeks.

“We are almost half way through November and must be prepared for the fact that the enemy may increase the number of drone or missile strikes on our infrastructure,” Zelenskiy said. “Russia is preparing for Ukraine. And here, in Ukraine, all attention should be focused on defence, on responding to terrorists on everything that Ukraine can do to get through the winter and improve our soldiers’ capabilities.”

Last winter about 10 months into Russia’s invasion of neighbour Ukraine, Russia made waves of attacks on power stations and other plants inked to the energy network, prompting rolling blackouts in widely separated regions.

Energy Minister German Galushchenko said on Saturday that Ukraine would have enough energy resources to get through the winter, but added: “The question is how much future attacks can affect supplies.”

Russian forces have ramped up attacks in eastern Ukraine in an attempt to gain ground near key frontline city Bakhmut, Ukrainian military officials said Sunday.

Moscow's troops have begun a push to regain territory near Bakhmut, the eastern mining city that was the site of the war's bloodiest battle before falling into Russian hands in May, the head of Ukraine's ground forces wrote on the Telegram messaging app.

Ukrainian troops had recaptured the heights over Bakhmut and made some advances west, north and south of the city since Kyiv launched its summer counteroffensive.

"Toward Bakhmut, the Russians have become more active and are trying to recapture previously lost positions. ... Enemy attacks are being repelled," Col. Gen. Oleksandr Syrskyi wrote in a Telegram update on Sunday afternoon.

A Russian Defense Ministry spokesman said Sunday that Russian forces over the previous day repelled five Ukrainian attacks near Klischiivka and Kurdyumivka, two small settlements lying south of Bakhmut. Lt. Gen. Igor Konashenkov made the claim at the latest of regular press briefings.

Ukraine's long-awaited counteroffensive has so far resulted in only incremental gains and heavy losses, with Ukrainian troops struggling to punch through Russian lines in the south. Meanwhile, Moscow's forces have attempted to press forward in the northeast, likely with a view to distract Kyiv and minimize the number of troops Ukraine is able to send to key southern and eastern battles.

Russian forces have recently advanced near Avdiivka, according to a US war think tank.

The Institute for the Study of War said Vladimir Putin’s forces temporarily intensified offensive operations in the area over the course of Friday and Saturday.

It said this is “likely to consolidate recent gains in the area”.

Ukraine's intelligence directorate said on Sunday that an explosion in the Russian-occupied town of Melitopol killed at least three Russian servicemen in an attack it described as an "act of revenge" by local underground groups.

The blast occurred during a meeting on Saturday of Russian officers in the town, a hub of Russian forces in the south, the directorate within the defence ministry said in a statement.

"This act of revenge, carried out by representatives of the local resistance, took place in the New Post offices seized by the Russians," it said.

There was no mention of the incident from Russian officials. Reuters was unable to verify the Ukrainian statement.

The intelligence statement said the meeting on Saturday at the local military headquarters was attended by Russian National Guard and FSB intelligence service officers.

"As a result of the explosion at least three National Guard officers were killed at the headquarters," the statement said. "Information of other enemy losses is being clarified."

The statement said police converged on the area and a burned-out car was later seen being towed through the town.

US President Joe Biden is facing two wars on two continents, and the fallout from each conflict will shape a second term even if the fighting ends before that.

The Russian invasion of Ukraine has been going on for almost two years, and Israel and Hamas began their latest clash about a month ago. Biden wants to send military support to Ukraine and Israel, something that he describes as "vital" to U.S. national security interests.

"History has taught us when terrorists don't pay a price for their terror, when dictators don't pay a price for their aggression, they cause more chaos and death and more destruction," he said in a recent Oval Office address.

His plans will require challenging congressional negotiations. Some Republicans are resisting more assistance for Ukraine after Congress has already approved $113 billion in security, economic and humanitarian resistance.

Both conflicts will likely require years of U.S. involvement. For example, Biden is looking for a new opportunity to push for a two-state solution in the Middle East, creating an independent Palestinian country alongside Israel.

A Ukrainian military officer coordinated last year’s attack on the Nord Stream natural gas pipeline, the Washington Post reported on Saturday, citing anonymous sources in Ukraine and Europe.

No one has taken responsibility for the September 2022 blasts, which occurred off the Danish island of Bornholm and ruptured three out of four lines of the system that delivers Russian gas to Europe.

Washington and NATO called it an act of sabotage, while Moscow said it was an act of international terrorism.

Roman Chervinsky, a former intelligence official who served in the Ukrainian military’s special forces, managed a six-person team but did not plan the attack, the Post reported. He denied involvement.

A spokesperson for Ukraine‘s military told Reuters he had “no information” about the claim. The Ukrainian foreign ministry and Kyiv’s domestic security service, the SBU, did not immediately respond to requests for comment.

His commanding officer at the time, Maj. Gen. Viktor Hanushchak, told Ukrainian media earlier this year that senior military leadership had signed off on the plot to lure the Russian pilot.

Ukraine‘s General Staff said that Russian troops were also continuing their weekslong push to encircle Avdiivka, an Ukrainian stronghold south of Bakhmut and a key target since the beginning of the war.

It’s considered the gateway to parts of the eastern Donetsk region under Kyiv’s control.

The General Staff said the air force was playing a key part in the latest Russian assault. Gen. Oleksandr Tarnavskyi, who leads Ukrainian troops fighting in and near Avdiivka, said Sunday that the attacking Russian forces were ramping up airstrikes, particularly those using guided bombs. He wrote on Telegram that Russian troops over the previous day had launched 30 airstrikes and 712 artillery barrages at the city and surrounding areas, and clashed almost 50 times with Ukrainian units.