Explosions rocked the area around one of Russia’s largest military hubs before dawn on Thursday, and local officials later said that air defenses had shot down two drones.
At least one blast was heard in the city of Rostov-on-Don, which is home to Russia’s southern military headquarters and is a command center for its forces in Ukraine. In June, the city drew world attention when mercenary fighters from the Wagner military company faced off with regular Russian soldiers there in a short-lived uprising.
On Thursday, Russian news outlets posted a series of videos showing an explosion in the center of Rostov-on-Don. The Russian Defense Ministry said that drone attacks in other regions were thwarted.
Vasily Golubev, the regional governor of Rostov, said debris that fell after air defenses downed the drones had damaged cars and buildings, injuring one person. One drone fell in the city center, he said in a post on the Telegram messaging app, listing an address that is across the street from the military headquarters. Another was shot down outside the city in the western part of the region, he said.
President Vladimir V. Putin of Russia has made several official visits to Rostov-on-Don since the start of the war. His most recent visit was on Aug. 19, when he received reports from Valery V. Gerasimov, the chief of the general staff of Russia’s armed forces, and various commanders and senior officers, according to the Kremlin.
As a matter of official policy, the Ukrainian government does not comment on whether it has had a hand in the growing number of strikes across the border in Russia. But officials in Kyiv have become increasingly vocal in defending such strikes as warranted. President Volodymyr Zelensky has described the strikes as a “fair and just” way to bring the war home to Russia.
Last week, a wave of exploding drones targeted six Russian regions, including an airfield near the border with Estonia, a NATO member, where military cargo planes were damaged. In recent days, the airports around Moscow have had to temporarily suspend flights nearly every morning because of drone activity.
The forays are a sign, analysts say, that even as Kyiv has begged Western allies to supply long-range weapons, its own arms makers have built a homegrown arsenal that is capable of hitting Russian territory at a great distance by land, air and sea.
The strikes in Russian territory have not caused remotely as much damage as Moscow’s deadly attacks on Ukrainian cities, which often target civilian areas.
On Thursday, for the fourth time in five days, Russia attacked Izmail, a port city on the Danube River, said Oleg Kiper, the head of the region’s military administration. Two people were injured, the local prosecutor’s office said.
On a visit to Ukraine on Thursday, the American secretary of state, Antony J. Blinken, praised “the extraordinary resilience of the Ukrainian people” while touring a school in the northern Chernihiv region, where Russian forces kept Ukrainian civilians hostage, including children, early in the war last year.
Earlier, Mr. Blinken, who spent two days in Ukraine before leaving Thursday night, met with state border guards near Kyiv and also with a demining team working to clear roughly 11 acres of unexploded ordnance that were scattered by an explosion. A day earlier, he met with Mr. Zelensky and announced more than $1 billion in new military and humanitarian aid to Ukraine.
As limited as the incursions onto Russian soil are, they may nevertheless be taking a toll.
Even before the latest strikes, Frederick B. Hodges, a former top U.S. Army commander in Europe, said that the attacks inside Russia were having a cumulative effect. They may be hurting the economy, he said, and heightening tensions in a Russian military command already unsettled by the Wagner mutiny and the setbacks in the war in Ukraine.
“You can be sure people are getting chewed out,” General Hodges said in an interview. “There is going to be a lot of turmoil in the command structure.”
Russia’s air defense systems, largely designed to counter NATO air power, have the ability to limit the effectiveness of the strikes, he said, but the Kremlin’s war planners may have to reposition aircraft and redeploy military assets to counter the growing Ukrainian threat.
“Those have to come from somewhere, so there is going to be a loss of protection somewhere,” General Hodges said.
Erin Mendell, Constant Méheut and Valeriya Safronova contributed reporting.