President Vladimir V. Putin of Russia made a rare visit to Belarus on Monday to strengthen his bond with the country’s president and his closest regional ally, Aleksandr G. Lukashenko, a fellow strongman who has been under growing pressure from Moscow to provide more support for the war in Ukraine.
Appearing together at a palace in Minsk after their talks, Mr. Putin and Mr. Lukashenko spoke about the need to withstand Western economic pressure. Mr. Putin said the two had also discussed the formation of a “unified defense space,” without describing what that would entail, and had agreed to continue joint military exercises.
Mr. Putin’s visit took place as Russia continued its nighttime bombardment campaign against Ukraine’s power plants and other crucial infrastructure, deepening the country’s misery. And the trip seemed certain to escalate concerns in Kyiv about the possibility of a fresh ground offensive that could use Belarus as a launching pad.
Ukraine has repeatedly warned in recent days that Russian forces could be preparing a new assault from Belarus aimed at trying once again to seize Kyiv, only about 55 miles from the Belarusian border, or at disrupting the flow of Western arms and aid into Ukraine from Poland.
Defense ministers from Russia and Belarus signed an unspecified agreement this month to strengthen military ties, and Belarus said last week that it was checking the combat readiness of its troops. The last time it did that was just days before Russia invaded Ukraine from its territory.
Mr. Putin continues to use Belarus to train and supply his battered forces in Ukraine.
Mr. Lukashenko said that Russia was also helping Belarus train its military pilots to fly planes with special payloads, without elaborating. He did not mention the possibility of sending Belarusian forces into Ukraine, a step he has so far resisted.
Mr. Putin and Mr. Lukashenko have met at least six times since the war began. Most of those meetings took place in Russia. This was Mr. Putin’s first trip to Belarus since 2019, according to Russian state media, and Mr. Lukashenko was waiting on the tarmac to greet him with a hug.
In a sarcastic remark that seemed to address the two countries’ international isolation 10 months into the war, Mr. Lukashenko called himself and Mr. Putin “both co-aggressors — the most harmful, toxic people on the planet.”
Mr. Lukashenko has been almost wholly reliant on Mr. Putin since the Russian leader helped crush street protests that erupted in Belarus in August 2020, after Mr. Lukashenko declared an improbable landslide victory in a contested election. He depends on Russia for financial, fuel and security assistance to maintain his 28-year grip on power. On Monday, the two presidents reached a deal on the price of subsidized Russian gas deliveries to Belarus, further bolstering Mr. Lukashenko.
“Are we able to defend our independence and sovereignty without Russia?” Mr. Lukashenko said. “No, we are not.”
As the talks began, Russia had just finished carrying out a wave of predawn attacks with Iranian-made drones on Kyiv and other Ukrainian cities, Ukrainian officials said, continuing a pattern of nighttime strikes that Moscow has adopted to try to evade Ukrainian air defenses.
Most of the exploding drones targeted power plants and other important infrastructure in Kyiv, where at least four loud explosions were heard. The city government issued warnings for residents to take shelter.
The Ukrainian Air Force said that 30 of at least 35 of the drones were destroyed before they reached their targets across Ukraine.
Kyiv’s mayor, Vitali Klitschko, said that critical infrastructure had been hit and that power and heat had been knocked out in some neighborhoods. In the region around the capital, three people were wounded and nine houses were damaged, the police said in a statement.
Ukraine’s national nuclear power company, Energoatom, said one of the Iranian drones had also flown over the Southern Ukraine Nuclear Power Plant shortly after midnight on Monday, posing a risk to the site.
“This is an absolutely unacceptable violation of nuclear and radiation safety,” the company said in a statement.
President Volodymyr Zelensky of Ukraine said the attacks had come from a shipment of Shahed drones that he said Iran had recently delivered to Russia. He cited the weapons in an address to European leaders gathered in Latvia, urging them to provide more support for Ukraine’s air defenses.
During the day, Ukrainians can use small arms to shoot down drones, said Yurii Ihnat, a spokesman for the Ukrainian Air Force. But in the darkness, he said, Ukraine needs expensive and limited missile systems that can track drones by radar.
Some military analysts have said that a flurry of military activity in Belarus, including the arrival of thousands of Russian troops ostensibly for training, could be part of an elaborate ruse aimed at forcing Ukraine to divert troops to the north from active fronts in the east and south of the country.
Konrad Muzyka, an independent defense analyst, said open-source intelligence suggests that Russia has 10,000 to 15,000 soldiers engaged in training activities in Belarus, although that is a small fraction of the number they had when they began the full-scale invasion.
The Institute for the Study of War, a Washington-based research group, said in a report published on Friday that a new Russian thrust into Ukraine was unlikely as “there are still no indicators that Russian forces are forming a strike force in Belarus.”
Still, Mr. Putin’s meeting with Mr. Lukashenko, according to the institute “will reinforce the Russian information operation designed to convince Ukrainians and Westerners that Russia may attack Ukraine from Belarus.”
The Kremlin’s spokesman, Dmitri S. Peskov, dismissed speculation that Belarus could become more directly involved in the war, telling reporters on Monday that such talk was based on “totally stupid, groundless fabrications.”
Mr. Peskov similarly dismissed warnings from the United States at the start of the year that Russia was planning to invade Ukraine, insisting that Moscow had sent troops to Belarus only for training exercises.
Marc Santora, Andrew Higgins and Maria Varenikova contributed reporting.
