Ukraine says it hit dozens of long-range bomber aircraft across Russia with drones that were smuggled in wooden shipping crates carried on truck beds into the country and then launched from nearby locations.
In comments to RFE/RL's Ukrainian Service, unnamed officials with the Security Service of Ukraine, known as the SBU, claimed as many as 40 bombers may have been hit in the June 1 attack.
The SBU later put out a statement claiming 34 percent of "strategic cruise missile carriers at the main airfields of the Russian Federation" were hit in the attacks with the damages totaling some $7 billion.
The drone operation appears to be a major embarrassment for Russia's military and intelligence agencies -- and the latest in a series of audacious attacks that Ukraine has pulled on Russian soil.
"An absolutely brilliant outcome. And an outcome produced by Ukraine independently," Ukrainian President Volodymyr Zelenskyy said, noting that the operation had taken more than a year and half to prepare.
"This is our longest-range operation," he added.
Russian officials had no immediate comment on the claims, but the Defense Ministry issued a statement saying air bases in five different regions had been targeted, and that at two of them "several aircraft caught fire."
Russian Telegram channels, meanwhile, published numerous photographs and videos showing drones taking off from truck beds, as well as some containers exploding or burning, in multiple locations.
The SBU, which said it will publish details of the operation at a later time, released video showing drones exploding into Tupolev bombers parked on tarmacs, while other videos showed plumes of smoke rising over several bases.
Strategic, long-range bombers have played a key role in Russia's war, firing long-range cruise missiles at Ukrainian targets well out of range of Ukrainian air defenses.
Governors in several Russian regions confirmed Ukrainian drone sightings, though it was unclear if any aircraft were hit.
Air bases in the northern Murmansk and central Ryazan regions were reportedly hit, as was a base in the Siberian region of Irkutsk, which is more than 5,200 kilometers east of the Ukrainian border.
Governor Igor Kobzeva said it was the first time a Ukrainian drone had been spotted in the region.
The SBU also released photographs that appeared to show wooden shipping containers containing numerous drones, stacked up in an undisclosed warehouse.
An SBU official, who spoke on condition of anonymity, said the agency shipped drones to Russia while making a separate shipment of what the official described as mobile wooden houses, or sheds.
Then, he said, "the drones were hidden [inside the sheds] that were already placed on trucks."
The roofs were then retracted and the drones launched, the official said.
More than 40 Russian aircraft were destroyed, the official claimed, including Tu-95 and Tu-22 M3 bombers.
Russian Missile Hits Ukraine Training Base
In Ukraine, meanwhile, a Russian missile hit a training base overnight, killing at least 12 troops and wounded dozens of others, Ukraine's Ground Forces command said.
The statement emphasized that there had been no gatherings of soldiers at the time of the attack. Russian forces in the past have targeted Ukrainian units gathering for ceremonies or unit muster, for example, prompting criticism from higher commanders
Still, the commander of the ground forces, Major General Mykhaylo Drapatiy, said he had tendered resignation in response to the attack.
"This is a conscious step dictated by my personal sense of responsibility for the tragedy at the 239th training ground, which resulted in the deaths of our soldiers," he wrote on Facebook.
It was unclear if Zelenskyy would approve the resignation. Drapatiy is a respected commander for, among other things, his command of defenses around the embattled city of Pokrovsk.
Elsewhere, Russia launched three strikes on the village of Ternuvate in the Zaporizhzhya, killing four people, local officials said on June 1.
Ivan Fedorov said that among the dead were three women, aged 18, 35, and 56.
The attacks by both sides come as negotiators from Kyiv and Moscow prepare for a second round of peace talks scheduled for June 2 in Istanbul.
The first round of talks last month ended with little tangible progress, although the two sides agreed to exchange hundreds of prisoners of war.
Russia's tempo of operations has picked up in recent weeks, and Ukrainian authorities have warned that Russia could be preparing a new offensive.
Zelenskyy said last week that Russia had amassed some 50,000 troops across the border from Ukraine's Sumy region. Officials have issued evacuation orders for scores of settlements in the region.
An initial round of talks on May 16 -- the first direct peace talks between since the weeks after Moscow launched the full-scale invasion -- ended with an agreement for a major prisoner exchange but with no progress toward bridging the wide gaps between the countries' positions on a path to peace.
Russia has rejected weeks of calls by Ukraine, the United States, and Kyiv's supporters in Europe for an extendable 30-day cease-fire and has kept up attacks even as it urges Ukraine to send negotiators to proposed talks in Istanbul on June 2.
Russia has said it would use the proposed June 2 meeting to outline its terms for a peace settlement. Kyiv has complained that Moscow had not shared its proposed conditions ahead of time.
"No one yet has any idea what Russians are coming with for the talks in Istanbul...and it does not look serious on their part," Zelesnkyy said in his May 31 nightly video address.
Russian officials have said the talks must address what Russian President Vladimir Putin calls the "root causes" of the war, a term he uses to question Ukraine’s right to exist and to seek limits on the size and strength of NATO.
Several NATO staffers and diplomats familiar with the talks told RFE/RL's Ukrainian Service that there currently are no active discussions about Moscow's demand for a written commitment not to expand the alliance further to the east.
