TALLINN, Estonia >> A drone attacked a skyscraper in central Moscow early Tuesday for the second time in around 48 hours, damaging the building’s facade and further underscoring the Russian capital’s vulnerability. Russian authorities accused Ukraine of staging the assault.

An adviser to Ukrainian President Volodymyr Zelenskyy tweeted that Moscow “is rapidly getting used to a full-fledged war,” without confirming or denying Kyiv’s involvement.

Russian officials have claimed that the repeated attacks on the capital region reflect failures in Ukraine’s counteroffensive to recapture Russian-occupied territory. Zelenskyy said over the weekend that “the war is gradually coming back to Russian territory,” but he stopped short of taking responsibility.

Russia’s Defense Ministry said it shot down two Ukrainian drones outside Moscow and jammed another, sending it crashing into a skyscraper and damaging the building’s facade. The attack happened in a business district of high-rise office buildings known as Moscow City, west of the Kremlin.

Moscow Mayor Sergei Sobyanin said the drone crashed into the same building that was damaged Sunday in a similar attack. IQ-Quarter, located 7.2 kilometers (4.5 miles) from the Kremlin, houses multiple government agencies, including the headquarters of the Ministry of Economic Development, the Ministry of Digital Development and Communications, and the Ministry of Industry and Trade.

The mayor said the attack on Tuesday did not result in any casualties.

It wasn’t clear why the same building was hit twice in a row. In both attacks, the Russian military said the drones that hit the skyscraper were jammed before crashing, which elicited questions from even the staunchest supporters of the Kremlin.

Margarita Simonyan, chief editor of the state-funded TV channel RT, said in a social media post that “a drone hitting the same tower for the second time in a row, where three federal ministries are located, at least requires explaining the comments that the electronic warfare downed them all.”

Asked about how protected the Russian capital is, given that supposedly jammed drones hit the same building, Kremlin spokesman Dmitry Peskov redirected the question to the Defense Ministry, saying only that “the threat exists and measures are being taken.”

Sobyanin said the drone that struck the building Tuesday hit the 21st floor, one of the floors housing the Economic Development ministry. Photos from the scene showed several panels of glass missing, exposing the charred insides of the building. According to the mayor, 150 square meters (about 1,600 square feet) of the building’s glass facade were damaged.

Russian news agency Interfax cited Darya Levchenko, an adviser to the economic development minister, as saying that the ministry’s staff worked from home Tuesday while damage to the office was assessed.

The Russian military also said Ukrainian forces tried to attack two of its warships in the Black Sea, using maritime drones. Three drones targeted two patrol vessels, Sergei Kotov and Vasily Bykov, 340 kilometers (210 miles) southwest of the Russian-controlled city of Sevastopol on the Crimean Peninsula, the Defense Ministry reported. All three drones were destroyed, the report said.

The governor of the Sevastopol region, Mikhail Razvozhaev, said a drone was shot down about 10 kilometers (6 miles) east of the city on Tuesday evening, causing a brush fire.

The attacks on Moscow and Crimea, which Russia illegally annexed from Ukraine in 2014, follow a deadly Russian missile strike on Kryvyi Rih, Zelenskyy’s hometown in central Ukraine.

Monday’s strike partially destroyed a residential building and killed seven people. Dozens more were wounded.

Russia’s land and sea border with Ukraine spans more than 2,200 kilometers (1,400 miles), meaning that much of the line separating the two countries is not covered by defense radar, which creates an opening for drones.

“Depending on where they are launched from, if there is a way to get through the initial line of defenses, then there will probably be a very poor ability to track them in real time,” said professor Justin Bronk, an expert in military air power and technology at the Royal United Services Institute, a defense think tank in London.

The most advanced defense systems around Moscow “are typically optimized for ballistic missile defense and are looking at targets and objects which are coming in at extremely high speeds and from very high angles,” Bronk said.

Unlike ballistic missiles, drones can fly low and slow. That presents a challenge for radar systems, which scan higher altitudes and filter out slow-moving objects such as birds.

In other developments Tuesday, Russian forces attacked Kharkiv, Ukraine’s second-largest city, with Iranian-made Shahed drones, according to Kharkiv Gov. Oleh Syniehubov.

One drone struck a three-story building at an educational institution in the Saltivka district, partially destroying the top two floors of the building, as well as the roof. No one was inside at the time.

Three more drone strikes hit the area of a sports complex in the Shevchenkivskyi district of Kharkiv. A two-story building in the complex was partially damaged, and a 63-year-old security guard was wounded, according to Syniehubov.

Russian forces shelled the city of Kherson and hit a medical facility, according to regional Gov. Roman Mrochko, killing a doctor and wounding one nurse.

“A young, talented doctor was killed, who was on his first day of work after internship. It was his first working day, which ended without even starting,” Tetiana Karchevych, Kherson region health department head, said at the site of the attack.

Ukraine’s presidential office reported Tuesday morning that at least 12 civilians had been killed in the country over the previous 24 hours, and 104 people injured.

The office reported that Monday’s attack on Kryvyi Rih killed seven people, including a 10-year-old girl, making it one of the deadliest attacks on civilians in recent weeks. Russian rockets struck a residential high-rise building and a university building in the attack, which also wounded 81 people, including seven children.

Hanna Arhirova in Kyiv, Ukraine, and Yuras Karmanau in Berlin, contributed to this report.