A man pushes a stroller in front of a damaged apartment building in Borodyanka, Ukraine, on Sunday. Russia claims to have destroyed several air defense systems in Ukraine over the weekend, in what appeared to be a new impetus for air supremacy and the elimination of weapons that Kyiv described as crucial in the face of a major new offensive in the east. In a strike announced Monday, Moscow said it had hit four S-300 launchers supplied by an unnamed European country. Slovakia gave Ukraine just such a system last week, but denied it had been destroyed. Russia has previously reported two strikes on similar systems elsewhere. The initial invasion of Moscow stopped on several fronts as it met fierce resistance from Ukrainian forces, which prevented the Russians from occupying the capital and other cities. Failure to gain full control of Ukraine’s skies has hampered Moscow’s ability to provide air cover to troops on the ground, limiting their progress and possibly exposing them to greater losses. By preventing their attack in many parts of the country, Russian forces are increasingly relying on city bombing. The war razed many urban areas, killed thousands, and left Russia politically and economically isolated. Ukrainian authorities accuse Russian forces of committing atrocities, including a massacre in the city of Bukha, outside Kyiv, airstrikes on hospitals and a rocket attack that killed at least 57 people at a train station. In Bucha on Monday, work on exhuming a mass grave from a churchyard resumed. Galyna Feoktistova waited for hours in the cold and rain hoping to recognize her 50-year-old son, who was shot and killed more than a month ago but eventually went home for some warmth. “She is still there,” said her surviving son, Andriy. Russia is now regrouping for a new impetus in the eastern Donbass region, where Moscow-backed separatists have been battling Ukrainian forces since 2014 and have declared independent states. Both sides are digging for what could be a devastating war of attrition. Russia has appointed an experienced general to lead the effort, according to US officials, although they do not see a man making a difference. Ukrainian President Volodymyr Zelenskyy, meanwhile, is calling for more Western help, saying his forces need more firepower to withstand the onslaught and repel Russian forces. Echoing comments in an AP interview, Zelensky said Sunday that next week could be crucial, with Western support for his country – or lack thereof – proving decisive. “To be honest, whether we can (survive) depends on that,” Zelensky said in an interview with 60 Minutes. “Unfortunately, I’m not sure we will get everything we need.” In a video speech to South Korean lawmakers on Monday, he specifically called for equipment that could shoot down Russian missiles. But these equipments could come under increasing attack as Russia seeks to shift the balance in the six-week war. Russian Defense Ministry spokesman Lt. Gen. Igor Konashenkov said the army used cruise missiles to destroy four launchers in the southern suburbs of the central city of Dnipro on Sunday. He said the army had also hit such systems in the Mykolaiv and Kharkiv regions. Lubica Janikova, a spokeswoman for the Slovak prime minister, denied on Monday that the S-300 system she had sent to Ukraine had been damaged. He said that any other claim is not true. It is not clear what the system contained, but a senior U.S. defense official said the Soviet-era system usually consisted of four launchers. The official spoke on condition of anonymity to provide information before the public announcement. None of the Russian allegations could be independently verified. Ukraine has specifically requested more S-300s in recent months, although it already had a number of Soviet-made systems and other long-range air defense systems. It has also received batches of portable western shoulder anti-aircraft guns, such as the Stingers, which are effective against low-flying aircraft. Austrian Chancellor Carl Nehamer was scheduled to meet with Russian President Vladimir Putin in Moscow on Monday, following a meeting with Zelensky in Kyiv. Austria, a member of the European Union, is militarily neutral and is not a member of NATO. Questions remain about the ability of exhausted and discouraged Russian forces to gain ground after being repulsed in Kyiv by determined Ukrainian defenders. The British Ministry of Defense said on Monday that Ukraine had already repulsed several attacks by Russian forces in the eastern Donetsk and Luhansk regions – which are Donbass – resulting in the destruction of Russian tanks, vehicles and artillery. In Washington, a senior US official said Russia had appointed General Alexander Dvornikov, one of its most experienced military leaders, to oversee the invasion. The official was not authorized to be named and spoke on condition of anonymity. Russia does not generally announce such appointments and there has been no comment from Moscow. Dvornikov, 60, gained a reputation for being a ruthless leader of Russian forces deployed in Syria in 2015 to support the government of President Bashar al-Assad during the country’s devastating civil war. Until now, Russia has had no central warlord on the ground. But U.S. National Security Adviser Jake Sullivan, speaking Sunday on CNN’s “State of the Union,” downplayed the significance of the appointment. “What we have learned in the first weeks of this war is that Ukraine will never surrender to Russia,” Sullivan said. “It does not matter which general Putin tries to appoint.” Western military analysts say the Russian offensive is increasingly focused on eastern Ukraine – an arc that stretches from Kharkiv, Ukraine’s second largest city, in the north to Kherson in the south. On Sunday, Russian forces bombed government-controlled Kharkov and sent reinforcements to Izyum in the southeast to try to break through Ukraine’s defenses, the Ukrainian military said. The Russians also continued the siege of Mariupol, a key southern port in Donbass that had been under siege almost since the beginning of the war. Oleh Synyehubov, Kharkiv’s regional governor, said Monday that Russian bombings had killed 11 people in the past 24 hours, including a 7-year-old boy. The Institute for the Study of War, an American think tank, has predicted that Russian forces will “resume offensive operations in the coming days” by Izyum in the campaign to seize the Donbas, which includes the industrial heart of Ukraine. But he said the result “remains very much in question”. In Mariupol, Russia has deployed Chechen fighters, who are known to be extremely tough. The occupation of the city in the Sea of Azov would give Russia a land bridge on the Crimean peninsula, which Russia occupied from Ukraine and annexed eight years ago. In a video posted on his Telegram channel, Chechen leader Ramzan Kadyrov said Russian forces would launch a new offensive in Mariupol as well as in Kyiv and other cities. “Our offensive work will not only be in Mariupol, but in all other settlements, towns and villages,” he said. The residents of Mariupol have been deprived of food, water and electricity since Russian forces surrounded the city. Hundreds of thousands have fled, although Russian attacks have also thwarted evacuation missions. Vladislav Usovich, an 18-year-old conscript serving in the Russian-backed separatist forces, walked slowly with other fighters through residential areas around a factory in Mariupol on Sunday. “I thought it would go better, I thought it would be faster. “Everything is going slowly,” he said. “The Ukrainians are prepared fighters. “NATO trained them well.”