LONDON -- Russia is ramping up a grinding summer offensive in eastern Ukraine as Kyiv appeals to President Donald Trump for more military aid and intensified pressure on Russian President Vladimir Putin. Putin's latest push comes at a pivotal moment. Prevailing Ukraine-skepticism inside the Trump administration may be softening as White House frustration with the Kremlin grows -- but the president, who has in the past often acted in an unpredictable and transactional manner toward Ukraine, could still turn away from Kyiv. The European Union is still marshalling its vast industrial resources to help arm Ukraine, having already taken the lead in economic support for the war-weary nation. The bloc does not yet appear willing or able to shoulder the military burden so far mostly carried by the U.S. And at home, President Volodymyr Zelenskyy's apparent efforts to weaken anti-corruption bodies sparked street protests, while the armed forces' persistent manpower strain is necessitating difficult conversations about widening conscription brackets and hardening responses to draft-dodging. Russia's now-routine huge drone and missile attacks on Ukraine's cities are also increasing the pressure. What began as a broad Russian push all along the 600-mile front in eastern and southern Ukraine now appears to be narrowing into three axes of attack -- in the northeastern Sumy region and in the eastern Donetsk Oblast cities of Pokrovsk and Kostyantynivka, two important defensive hubs. "The Russians did not have a very clearly definable beginning for this summer campaign season," Pasi Paroinen, an analyst at the Finland-based Black Bird Group told ABC News. "They intensified their attacks pretty much almost all across the front line around May and towards June." "The Russians are probably starting to reach the point where they will start to pick up the pace of the offensive," Paroinen said. "Overall, it is likely that the trend is going to be worse and worse for the Ukrainians over the summer. I don't see the Russians running out of steam anytime soon." In Donetsk, Ukrainian troops are engaged in a familiar dance, slowly ceding territory while seeking to inflict maximum damage on attacking Russian units. The costs appear high for Moscow's forces, with the Ukrainian army claiming to be "eliminating" around 1,000 Russian troops per day. But the attacks keep coming. There is growing alarm over Pokrovsk and Kostyantynivka, which are at risk of being surrounded in the coming months. Russia has been struggling to take Pokrovsk for more than a year, but recently has managed to advance on the city's flanks. This means Russian forces are increasingly threatening Ukraine's supply lines, in part by intensively targeting them with drones. Russia last week also claimed to have finally captured Chasiv Yar, an important heavily fortified town that Ukraine has used to choke Russia's offensive towards Kostyantynivka for over a year. Although most independent analysts say the Russian claim was premature, the Washington D.C.-based Institute for the Study of War assessed Russia will "likely complete the seizure of Chasiv Yar in the coming days." It will open up more opportunities for Russia to strangle Ukrainian forces in Kostyantynivka. MORE: Trump envoy Witkoff to head to Russia for 'last chance' Ukraine ceasefire talks Many analysts remain skeptical that the mauled and plodding Russian forces are capable of achieving a significant breakthrough. But some Ukrainian and independent military analysts worry that small but accumulating Russian advances could snowball into a bigger crisis for Ukraine's frontline, as manpower shortages continue to worsen. The advances may also help persuade Putin he is right to maintain the war and continue rebuffing ceasefire demands from Kyiv and Washington. Earlier in the summer, Russian forces attacking in small groups with light vehicles -- among them motorcycles -- scored significant success, allowing them to "mitigate the effects of the Ukrainian drones by launching a lot of simultaneous assaults," Paroinen said. But those Russian units are now largely spent, he added, with time needed to train and equip their replacements. "In general, the basic tactics are relying even more on the manpower advantage and using those small infantry attacks in combination with heavy usage of firepower," Paroinen said. In Sumy, at least, Ukrainian forces say they have largely stalled the Russian push. Maj. Oleh Shyriaiev -- the commander of the 225th Separate Assault Regiment fighting in Sumy -- told ABC News that Russian forces pushed between 9 and 13 miles into the northeastern border region in places, though said that forward momentum has largely been arrested. In recent weeks, the 225th has advanced, taking back the villages of Kindrativka and Andriivka. But the Russians are also still pushing, Shyriaiev said. "They are trying to move forward in small groups" towards the city of Sumy, Shyriaiev said, speaking to ABC News from close to the front line while visiting wounded members of his unit at a medical facility. "Their troops constantly get new replenishments and they are still trying with so-called 'meat assaults' to find a way to move forwards," he added of the enemy forces, using a common term in Ukrainian military parlance to refer to Russia's unsophisticated, high-casualty assault operations. The city of Sumy, which is around 15 miles from the current front line, is already under fire. MORE: 'They do not surrender': Ukraine commander details fight with North Koreans in Russia "Sumy is under constant threat," Yuriy Boyechko, the founder and CEO of the Hope for Ukraine charity, told ABC News. "Russian drones terrorize the city daily," added Boyechko, whose teams have been evacuating local residents from areas close to the fighting. "The area is relentlessly bombarded by missiles and smaller drones continue to target civilians," he added. Russian forces in Sumy are striking along roads, through towns and woodlands, Shyriaiev said. The later summer weather may offer new opportunities for Moscow's troops, with secondary roads and other terrain dried out and offering new avenues of assault. Among the Russian units in Sumy are some of the most celebrated within Russia -- and among the most reviled in Ukraine due to their alleged involvement in a litany of war crimes. The 155th Guards Naval Infantry Brigade, 40th Separate Guards Naval Infantry Brigade and 76th Guards Air Assault Division are all in the fight, Shyriaiev said, though added that even Russia's elite units are relying on "meat assaults." "All the advances that they were able to achieve were done at the cost of using a lot of infantry," the commander said. "Against every one fighter of the defense forces of Ukraine, they are putting up 10 people on the Russian side." Paroinen suggested Russian forces are thin on armor. "The Russians have been using fewer and fewer heavy vehicles like tanks and infantry fighting vehicles," he said. "In Sumy, for example, they have been almost completely absent." Perhaps the most punishing aspect of the Russian offensive is its use of so-called "glide bombs," munitions dropped by jets from as far as 25 miles from the front line, making it difficult for ground-based anti-air weapons to stop them. Glide bombs have been a constant danger to Ukrainians holding positions along the front, but recent months have seen the Russian air force significantly increase their use. "They really are just methodically pounding every Ukrainian position, using five to 10 glide bombs just to destroy one treeline," Paroinen said. "The accuracy of these weapons is enough to effectively dismantle the defenses." Addressing the glide bomb problem could prove "really important" for Ukrainian defenders, he added. Shyriaiev concurred, saying glide bombs are making operations "very difficult" in Sumy. "Every time our regiment has any type of success, the Russians are using glide bombs against them. They consider it worthwhile to use a glide bomb when they see a group even as small as four to five servicemen," he said. "When we were liberating Andriivka and Kindrativka, they were using 30 to 50 glide bombs in a 24-hour period," Shyriaiev recalled. Throughout Russia's full-scale invasion, Ukrainian forces have sought to address Russia's manpower advantage through technological superiority -- both by adopting Western-produced arms and innovating new weapons, prime among them first-person view drones. President Donald Trump's return to office has thrown the continuation of American military aid into doubt. Still, Putin's relentless long-range strikes and frontline offensives have prompted Trump to promise new weapons for Ukraine -- much to the relief of Kyiv. American weapons are still making a real difference at the front, Shyriaiev said. "All of the successful actions that we have, all of this success in liberating our territory that we have been able to achieve, have been accomplished with the help of American weapons," he explained. HIMARS missiles, Javelin anti-tank weapons, Claymore mines, grenades and 5.56 mm-caliber American assault rifles are particularly valued by the 225th, he said. Alexei Baranovsky, a military journalist and a veteran of the pro-Ukraine Freedom of Russia Legion, told ABC News that long-range defensive and offensive weapons could help shift the battle in Kyiv's favor. "We need air defense systems -- Patriots -- to protect our cities from missile and drone strikes," he said. "Second, long-range missiles to strike deep into Russian territory at military facilities," Baranovsky added, suggesting the American-made Tomahawk cruise missile would be top of Ukraine's shopping list. Soldiers at the front are hoping Trump's frustration with the Kremlin boils over into a sustained policy pivot in supporting Kyiv's war effort, Shyriaiev said. In July, the president set a 50-day ultimatum for Putin to accept a ceasefire or risk new U.S. economic measures. Trump then shortened the window to "10 to 12 days," citing "disappointment" at Russia's continued attacks. "Fifty days is nowhere near enough for Putin to make any meaningful advances or have any type of spectacular success in the Sumy, Kharkiv and Donetsk directions, which is where the main thrusts of his offensive are happening," Shyriaiev said. "I am sure that we will be victorious -- and we will be victorious with the help of the United States," Shyriaiev added. MORE: Russia launches 6,400 drones, missiles into Ukraine in record-breaking month Nonetheless, Ukraine is suffering from severe manpower strain. Discussions continue in Kyiv about broadening conscription brackets in a bid to fill the ranks, a divisive and politically sensitive subject. "People are exhausted, there's no disputing that," Shyriaiev said. "But we would like to finish this war so that our children won't have to fight it again later." As to the swathes of Ukraine already lost to the invading Russian troops, the commander acknowledged it will be a "difficult" and "long process" to reclaim it. "For that, we need long-range weapons so that we would be able to strike the enemy's logistic pathways, their military industry centers, their oil processing industry and all of the places where their army is amassing," he said. "Plus, of course, we need the intelligence help from the United States." ABC News' Patrick Reevell contributed to this report.
