WASHINGTON, D.C. -- Russia dramatically intensified missile and drone attacks across Ukraine this month in an effort to sap Ukrainians’ morale – but it is also stepping up ground attacks in many areas along the long frontline, according to Ukrainian officials and analysts.

Some of those attacks have succeeded, with Ukrainian units in Donetsk and the north falling back from some positions, while some rural areas in the south have also been lost.

But Ukraine’s own enhanced use of drones, deployed in several layers on the battlefield, has helped Kyiv inflict heavy losses on the opposing forces with minimal casualties among its own troops. They may become even more critical in the months to come.

The Ukrainians are trying to expand their own drone industry to create defensive corridors along key sections of the front line, often dubbed the “drone wall.”

Meanwhile, ignoring US President Donald Trump’s efforts to secure a ceasefire, the Kremlin is pursuing a two-pronged strategy aimed at forcing Ukraine to admit defeat – destroying its cities from the sky and whittling away its defensive lines on the ground.

Russia has sharply expanded its own drone and missile production in the past year, allowing for mass attacks using several hundred projectiles at once. The Russian strategy seeks to overwhelm Ukraine’s air defenses with scores of low-cost drones so that simultaneous missile strikes can succeed.

On the ground, Russian forces are probing Ukrainian defenses along many parts of the frontline simultaneously, from Zaporizhzhia in the south to Sumy in the north, advancing into abandoned villages and across open countryside in small numbers.

The Russians are not rolling through Ukrainian defenses but gnawing away at them, using cars and motorbikes and scattered infantry platoons.

Russian forces have advanced an average of roughly 14 square kilometers (5.4 square miles) per day so far this year, according to the Institute for the Study of War (ISW) in Washington. This rate implies they’d need nearly four more years to complete the occupation of the four regions illegally annexed by Moscow: Donetsk, Luhansk, Zaporizhzhia and Kherson.

Those are the Kremlin’s oft-stated goals, but it is also trying to instil a sense among Kyiv’s allies of Russian superiority over Ukrainian forces.

Much of the fighting is in Donetsk, with the Russians still determined to seize the entire region – unless it is handed over in peace negotiations, which is a non-starter for Ukrainian President Volodymyr Zelensky.

The Russian Defense Ministry claimed Tuesday that a village south of the key town of Kostiantynivka had been taken. ISW assesses that Russian forces seized roughly 65 square kms of territory - but remain incapable of intensifying offensive operations in several different directions simultaneously.

“The main Russian effort into the summer will once again be against the key towns of Kostyantynivka and Pokrovsk” in Donetsk, according to Jack Watling, a senior research fellow at the Royal United Services Institute (RUSI) in London.

Hundreds of miles to the north, Russian units have edged a few kilometers into the Sumy region.

Zelensky told journalists Tuesday that the Russians are “now amassing troops in the Sumy direction. More than 50,000. We understand that. But we are making progress there.”

Zelensky said the Russians wanted “to build this buffer zone, as they call it, 10 kilometers (6.2 miles) deep into Ukraine,” but lacked the capability.

The Russians are supporting these operations with missile and air-launched guided-bomb attacks.

The attacks into Sumy follow a Kremlin directive on May 21 that the military create buffer zones inside northern Ukraine – in Sumy and Kharkiv regions. That came when President Vladimir Putin visited Russia’s Kursk region across the border, part of which had been seized by a Ukrainian incursion launched from Sumy last summer.

Capturing Sumy’s regional capital is probably beyond the Russians – the terrain is thickly forested. But through their attacks, the Russian military can prevent the Ukrainians from redeploying units to Donetsk.

Further east there’s also been an uptick in fighting around Vovchansk in Kharkiv region in recent days.

Across the 1,000-kilometer (621-mile) frontline, according to analysts, the Ukrainian military has to decide which areas are under greatest threat, where to withdraw, how to redeploy – even as many brigades are seriously under-strength more than three years after the Russian invasion.

The manpower balance is still very much in Russia’s favor, despite its heavy losses. Putin recently claimed that 60,000 volunteers are being recruited every month. Observers believe this is likely exaggerated but signing-up bonuses that dwarf civilian wages in Russia make military service an attractive option.

Ukraine’s military chief, Oleksandr Syrskyi, said earlier this month that Kyiv faced “a combined enemy grouping of up to 640,000 personnel,” higher than at the outset of the invasion. Zelensky said in January that Ukraine had 880,000 soldiers, “but 880,000 are defending the entire territory. Russian forces are concentrated in certain directions.”

Russian recruitment “has exceeded Kremlin targets for every month of 2025,” according to the RUSI analyst Watling. “Having shuffled commanders and built-up reserves of equipment, Russia is now set to increase the tempo and scale of attacks.”

But for every square kilometer of Ukrainian land that Russia captures, Moscow is probably losing about 100 men, according to Western assessments.

Layers of drones

Above and behind the frontlines as well as in the air campaign being waged by Moscow, the development and deployment of drones will continue to be critical.

The recent Russian advances in Donetsk, while incremental, were enabled by the tactic of isolating the battlefield – cutting Ukrainian units from supplies through drone strikes on supply vehicles up to 30 kilometers (18.6 miles) from the front lines.

Ukrainian defenses are heavily reliant on layers of drones. The Ukrainians are developing a concept sometimes dubbed the “drone wall,” designed to “provide a continuous defensive corridor of drones along Ukraine’s most vulnerable frontiers to inflict significant casualties on Russian forces,” according to Mick Ryan, author of the blog Futura Doctrina.

Konrad Muzyka, a defense analyst at Rochan Consulting, says that “Ukrainian forces are increasingly lethal with drone-artillery coordination. Russian assaults — motorcycle-based and armored — were defeated across several fronts with minimal Ukrainian losses” in April.

But Ryan points out that an effective drone wall will require integration “and probably AI-assisted decision-making and analysis,” as well as integration with electronic warfare.

And it’s a two-way street. Ukrainian drones are “guided by small radar, and Russia is now systematically working to locate and target these radar stations,” Watling writes.

Zelensky said Tuesday that Russia plans to ramp up production of Shahed attack drones to between 300 and 350 per day. Asked whether there may come a time when Russia fires 1,000 drones in one day, he replied: “I cannot say that this will not happen.”

Sending drones in their hundreds saturates air defenses, as they accumulate over a target area. Russia has also developed drones that can evade Ukrainian jamming and can fly higher and faster than earlier models. Ukrainian analyst Oleksandr Kovalenko said last week that one Shahed had been observed at a record altitude of 4,900 meters.

According to Zelensky, Ukraine is now deploying F-16 and Mirage fighter jets to supplement air defenses. “We are also moving towards drone-to-drone interceptors,” he said Tuesday.

Ukraine’s former military chief, Valerii Zaluzhnyi, says Ukraine must wage a “high-tech war of survival” in which drones play a critical role, to “make the economic burden of the war unbearable for Russia.”

Speaking to a Kyiv forum last week, Zaluzhnyi – now Ukraine’s ambassador to London - said that his country had failed to exploit innovations “where yesterday we were ahead of the enemy. The enemy has already outpaced us.”

Analysts cite Russia’s growing use of short-range fiber-optic drones that can’t be jammed as one example of the technological race. Ukraine is yet to scale up the use of such drones, which rely on millimeters-thick, but miles-long, optical fibers.

Zelensky denied Ukraine was losing the drone war.

“We will have the same number of drones as the Russians, 300-500 per day - we are very close to it,” he said.

The issue was not production, Zelensky said – it was financial. As Ukraine seeks to produce more of its own weapons – often in association with Western manufacturers, Zelensky added: “I would like to see us receive $30 billion to launch Ukrainian production at full capacity.”

But that is a long-term goal.

Watling, from RUSI, envisages a tough few months for Ukraine that “will place a premium on the efficiency of Ukrainian drone and artillery operations, the ability of Ukrainian commanders to preserve their troops, and the continuity of supplies flowing from Ukraine’s international partners.”

The continuation of US supplies is unsure as Trump blows hot and cold about whether Washington should continue helping Ukraine defend itself.

Putin is “desperately seeking to prevent the future supply of Western military aid to Ukraine,” according to ISW, “as well-resourced Ukrainian forces have consistently demonstrated their ability to inflict unsustainable losses on Russian forces.”

Innovation and tactical agility will be as influential as brute force as the war enters its fourth summer.

CNN’s Kosta Gak and Victoria Butenko contributed reporting.

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