A drone attack that targeted Moscow today exposed glaring breaches in its air defenses and underlined the capital’s vulnerability as more Russian soil comes under fire amid expectations of a Ukrainian counteroffensive.

The attack, which lightly damaged three apartment buildings, angered Russia’s hawks, who scathingly criticized President Vladimir Putin and the military brass for failing to protect the heart of Kremlin power more than 310 miles from the front line.

Five of the eight drones that took part in the raid were shot down, the Defense Ministry said, while three others were jammed and forced to veer off course. Some Russian media and bloggers alleged a larger number of drones were involved, but those claims couldn’t be verified.

The attack followed a May 3 drone strike on the Kremlin that lightly damaged the roof of the palace that includes one of Putin’s official residences. Other drones have crashed near Moscow in what Russian authorities described as botched Ukrainian attempts to attack the city and infrastructure facilities in the suburbs.

Last week, the Russian border region of Belgorod was the target of one of the most serious cross-border raids since the war began, with two far-right pro-Ukrainian paramilitary groups claiming responsibility. Officials in the southern Russian city of Krasnodar near annexed Crimea said two drones struck there Friday, damaging residential buildings. The attacks also drew calls for bolstering Russia’s borders.

Ukrainian authorities rejoiced over today’s drone attack but customarily avoided a claim of responsibility, a response similar to what they said after previous attacks on Russian territory.

In a sarcastic tweet, Mykhailo Podolyak, an adviser to Ukrainian President Volodymyr Zelenskyy, said that “even artificial intelligence is already smarter and more far-sighted than the Russian military and political leadership.”

The Russian military pummeled the Ukrainian capital of Kyiv and other cities with cruise missiles and exploding drones for the past three nights, a significant spike in such attacks that have been regularly launched since October. The Ukrainian military said it shot down most of the missiles and remained coy about reporting damage from the strikes.

Putin cast the attack on Moscow as a Ukrainian attempt to intimidate its residents. He said Moscow’s air defenses worked as expected, but admitted that protecting a huge city is a daunting task.

“It’s clear what needs to be done to beef up air defenses, and we will do it,” he added.

Military watchers said the drones used in the attack were relatively crude and cheap but could have a range of up to 1,000 kilometers (over 620 miles). They predicted more could follow.

Some of the drones seen flying toward Moscow were the Ukrainian-made UJ-22s, capable of carrying explosives; others spotted in the skies near Moscow were similarly small vehicles.

Mark Cancian, a senior adviser with the Center for Strategic and International Studies International Security Program, noted that part of the reason why drones could make it all the way to Moscow undetected was because Russian air defenses are mostly focused on fending off attacks by more sophisticated weapons.

“They are oriented on missiles, ballistic missiles, regional missiles, aircraft, bombers, but not short-range drones, you know, which might be flying very low over the ground,” Cancian told The Associated Press. “The Russian air defense was just not designed to do this.”

The Russian military will likely move some of its air defense assets away from the front line to help protect Moscow, Cancian said, a move that would weaken Russian troops in the face of a Ukrainian counteroffensive.

“That’s good for the Ukrainians in the sense that they’re pulling these systems away from other areas where they could be used maybe from front-line units,” he said.

The Kremlin’s muted response to the attack irked some hawkish commentators and military bloggers in Moscow, who had criticized the Russian leadership for failing to mount a stronger response.

Yevgeny Prigozhin, the maverick millionaire head of the Wagner private military contractor that plays a key role on the battlefield in Ukraine, scolded the Russian military leadership and denounced them as “scum” and “swine” for failing to protect Moscow.

“You, the Defense Ministry, have done nothing to launch an offensive,” Prigozhin said in a statement released by his office. “How dare you to allow the drones to reach Moscow?”

Ramzan Kadyrov, the strongman leader of the Russian province of Chechnya who sent forces from the region to fight in Ukraine, urged the Kremlin to declare martial law nationwide and use all its resources in Ukraine “to sweep away that terrorist gang.”

Some Kremlin watchers noted that Putin’s calm reaction that contrasted with angry statements from Russian hawks reflects his belief that the public won’t be unsettled by the attack.

“Putin has talked repeatedly about the Russian people’s remarkable patience and tenacity,” Tatiana Stanovaya of the Carnegie Endowment said in a commentary. “No matter how defiant another Ukrainian attack is, Putin doesn’t think that it could provoke public discontent with the government.”

She noted that while playing down the strikes makes the authorities look “embarrassed and helpless,” it fits Putin’s course to drag out the conflict.

James Nixey, the director of the Russia and Eurasia program at Chatham House, said today’s attack signaled a growing Ukrainian determination to launch strikes deep inside Russia and predicted more will come.

“This is not the first and it’s not the last,” Nixey told AP. “The Ukrainians are in various respects flexing their muscles, seeing what they’re capable of hitting back. It is one more part of the Ukrainian play to ensure that they are not just playing defense, but they can play some offense as well.”

Despite the loud calls for revenge, the Russian military can’t do much more than what it has been doing since starting the war, Nixey noted.

“The reality is that Russia does have limits in what it can do. It’s got limits on manpower, limits on its finances, limits on its artillery munitions, missiles, drones, everything,” he said. “They’re already expending all their efforts, all their monies, all their treasure, all their blood if you like on prosecuting their war in Ukraine.”