Analysis by Nick Paton Walsh, Andrew Carey, Victoria Butenko, Yulia Kesaieva and Olga Voitovych

Updated 12:16 PM EDT, Wed May 1, 2024

Members of the Steppe Wolves, of the Voluntary Formation of the Zaporizhzhia Territorial Community, prepare a small handmade multiple rocket launcher for firing toward Russian troops near a frontline, amid a Russian attack on Ukraine on April 27, 2024. ReutersCNN — 

The five-month wait before US Congress approved $61 billion in military aid to Ukraine may have caused lasting damage that will be felt on the frontlines for months to come.

Russian forces have used the “artillery drought” hampering Ukraine’s defenses since December to push forward on the eastern front near Avdiivka, making the largest advance since the early months of the war. Moscow’s progress has prompted warnings from senior Ukrainian military officials of a possible threat to Kyiv’s supply lines and hubs in the east, which are now perilously close to being in range of superior Russian firepower.

The bleak news of progress comes ahead of an anticipated Russian offensive in late May, which could threaten Ukraine’s presence in the Donetsk region and hard-fought, if modest, gains towards the occupied port city of Mariupol. Russia has thrown vast resources at weak Ukrainian defenses across the eastern frontlines, pushing toward three key points: the vital military hub of Pokrovsk, west of Avdiivka; the strategic heights of Chasiv Yar, near Bakhmut; and  Kurakhove in the southeast.

On February 17, Ukraine announced it had withdrawn from Avdiivka, a town battled over for a decade, one which Russia appears to have sacrificed hundreds of troops to take. Yet Moscow’s advance did not stop there. Over the next 10 weeks, as a CNN map and analysis by the Ukrainian monitoring group DeepStateMap shows, Russian forces slowly took village after village to Avdiivka’s west, taking advantage of Kyiv’s failure to build fortifications and reluctance to publicly state the extent of their territorial losses in that area.

The fall of Avdiivka, Ukraine

Avdiivka has been on the front line since 2014 when pro-Moscow separatists seized large portions of the Donbas region, including the nearby city of Donetsk. Ukrainian forces had managed to hold the town — with only small Russian gains — for two years until Feb. 17, 2024 when they withdrew from the area.

Notes: “Assessed” means the Institute for the Study of War has received reliable and independently verifiable information to demonstrate Russian control or advances in those areas. Russian advances are areas where Russian forces have operated in or launched attacks, but they do not control them. “Claimed” areas are where sources have said control or counteroffensives are occurring, but ISW cannot corroborate or demonstrate them to be false.

Sources: The Institute for the Study of War with AEI’s Critical Threats Project

Graphic: Lou Robinson, CNN

Only on Sunday did the top Ukrainian military commander, Oleksandr Syrskyi, admit the fall of a series of villages that his subordinates had insisted for days were still contested. The resulting fallback showed Russian forces had, in just over two months, made the most substantial and swift progress since July 2022’s advances near Severodonetsk, according to a CNN analysis.

The Ukrainian reluctance to admit these losses led to public criticism from some pro-Ukrainian military bloggers and analysts. DeepStateMap, which updates the frontline situation daily, showed significant losses near Avdiivka. One of the group’s founders, Ruslan Mykula, told CNN they spoke out because they had felt a military “spokesperson has the opportunity to check the real situation, but he [still] provides untrue information and this undermines our credibility.”

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Mykula said the Russian advances near Ocheretyne, a village taken by Russia in the past weeks west of Avdiivka, are “a tactical success so far,” but could become “a strategic one.” He added: “In the current situation, it will be very difficult to stop the enemy because it is pushing where the defense was not paying enough attention.”

He said there was a lack of defensive fortifications along the Avdiivka “entire left flank” — which would effectively mean open plains are now vulnerable almost as far as a key highway that leads to the strategic Ukrainian hub of Pokrovsk.

Tuesday’s update from the Ukrainian general staff said their forces were defending a series of villages much closer to Pokrovsk than is comfortable. Tuesday’s presidential address from Volodymyr Zelensky demanded a “significant acceleration of [Western] supplies to significantly strengthen the capabilities of our soldiers.” He said Kyiv’s defenses needed a “strength that must prove itself in the Pokrovsk direction,” along with other perilous frontlines to the south near Kurakhоve, but also to the northeast near Kupiansk.

Further Russian advances towards Kurakhove in the southeastern part of this frontline could imperil gains made by Ukraine during the summer counteroffensive. To the north, Russia is regularly bombarding Ukraine’s second-largest city, Kharkiv, but also pushing hard along the frontlines near Kupiansk, to reoccupy territory liberated by Ukraine in a lightning advance in the late summer of 2022.

Ukrainian servicemen of the 25th Separate Airborne Brigade load a Marder infantry fighting vehicle near a frontline in Donetsk in April 29, 2024. REUTERS/Oleksandr Ratushniak Oleksandr Ratushniak/Reuter

Ukrainian officials have also warned publicly about the threat to Chasiv Yar, a small town near the city of Bakhmut, brutally torn from Ukrainian control last May. Chasiv Yar sits on a hill, and Lt. Col Nazar Voloshyn, spokesman for the Ukrainian Khortytsia command, said Tuesday on Ukrainian television that Russian forces were aiming to push along the canal near it, and seize it to gain a strategic advantage over vital nearby Ukrainian military towns.

“It would be very important for them to take Chasiv Yar before we receive foreign aid … when we stop having a shortage of ammunition,” Voloshyn told Ukrainian television. “If the enemy captures the dominant heights and the occupiers gain a foothold there, it will be a big problem for us, because Kostiantynivka, Kramatorsk, Sloviansk and Druzhkivka will immediately come under attack.”

People visit an exhibition, displaying armored vehicles and equipment captured by the Russian army from Ukrainian forces, at Victory Park open-air museum in Moscow, Russia, on May 1, 2024. REUTERS/Evgenia Novozhenina Evgenia Novozhenina/Reuters

If those four towns, which sit along the same highway, were to come under serious threat of capture, Russia’s goal of control over the entire Donetsk region would come much closer to fruition.

Yurii Fedorenko, commander of the Achilles attack drones company at the 92nd separate assault brigade in that area, said the next two months marked a “window of opportunity” for Russian forces. He said Russian forces had realized Ukraine will soon “have the necessary air defense assets and the necessary range of ammunition concentrated on the frontline, which will make it impossible for the enemy to perform tasks with the intensity it has now.”