After a week of heavy fighting, the true tests of Kyiv's counteroffensive lay ahead, with Ukrainian troops still far from Russia's main defensive line and the bulk of prepared forces still in reserve.
Ukraine launched the primary phase of its long-awaited operation in two areas along the southeast front last week, retaking seven villages and losing infantry fighting vehicles and tanks from the West.
According to Rob Lee, a senior fellow at the Foreign Policy Research Institute and one of the analysts who have reported fatalities on both sides based on satellite and photographic evidence, "a lot of it will come down to attrition on both sides."
"The risk for them (the Ukrainians) is that they will suffer too much attrition before reaching the (Russian) defensive line, making it difficult to breach and exploit it."
Ukrainian personnel should be protected by Western equipment such as battle tanks and armored vehicles, according to President Volodymyr Zelenskiy.
From the border of western Russia to occupied Crimea on the Black Sea, Russia has prepared tens of thousands of defensive positions, including minefields, anti-tank ditches, rows of concrete "dragon's teeth" barricades, and trenches.
The positions, evaluated by Reuters using satellite imagery in April, are heavily concentrated in the strategically significant south, where Kyiv may seek to cut Russia's land bridge to Crimea and divide Kremlin forces.
According to military analysts, because Ukraine's counteroffensive forces are in reserve, Kyiv can observe where Russia commits soldiers to bolster its lines and strike in less well-defended areas, including the east.
Ben Barry, senior fellow for land warfare at the International Institute for Strategic Studies, stated, "Ukraine has options."
"It cannot achieve strategic surprise, but it will try to achieve operational and tactical surprise. This will necessitate concealment, camouflage, deception, and misinformation, which they successfully employed last autumn."
According to Lee, Moscow's strategy in the south likely seeks to maximize Ukrainian casualties before Kyiv can reach the main Russian defensive line approximately 10-15 km (6-9 miles) away.
He stated, "There is no point in fighting to the death or risking encirclement there."
Questions of Momentum
Ukraine has been preparing for the counteroffensive for at least six months after recapturing the major southwestern city of Kherson in November, a large portion of the Kharkiv region in September, and compelling Russian forces to withdraw from the vicinity of Kyiv in April.
According to analysts, the military created twelve armored brigades for the operation, nine of which were trained and equipped by the West. Typically, a brigade consists of between 3,500 and 4,000 soldiers. Ukraine has reportedly formed eight assault brigades of 40,000 soldiers conscripted by the Ministry of the Interior.
Konrad Muzyka, a military analyst based in Poland who closely follows the conflict, stated that only three of the twelve brigades had been spotted in combat in the southeast.
The major thrusts are approximately 80 kilometers east of the Kyiv-controlled towns of Orikhiv in the Zaporizhia region and Velyka Novosilka in the Donetsk region.
These thrusts may indicate that Ukraine's generals are set on Tokmak, an occupied Zaporizhzhia region approximately 25 kilometers from the front line. Melitopol is located 50 kilometers further away. Each community is severely fortified.
Near Velyka Novosilka, Ukraine liberated four villages, two of which were visited by Reuters on Tuesday and Wednesday, and two others, according to Deputy Defense Minister Hanna Maliar's Monday statement.
She said that along a 100-kilometer (60-mile) stretch of the southern front line, troops have advanced up to 6.5 kilometers (four miles) and occupied 90 square kilometers (35 square miles) of territory. Over the past twenty-four hours, she reported additional advances of 300 to 350 meters in various regions.
"Initially, they performed quite well," Muzyka stated.
"My primary concern five or six days into this main phase is that progress seems to have halted. The momentum they gained in the first few days has essentially vanished, and we do not know why.
Maliar has also reported advances on the eastern flanks of Bakhmut, which Russia claimed last month to have captured. Analysts deemed it implausible that this would become the primary focus of the Ukrainian offensive.
The counteroffensive is complicated by the paucity of air power in Ukraine. Kyiv has been lobbying the West for F-16 fighter aircraft for months, but their deployment is at least several months away.
Kyiv has imposed an embargo on information to improve operational security, making independent battlefield assessments difficult. Vladimir Putin of Russia has characterized Kyiv's attack thus far as a failure with significant casualties.
Images shared by Russian military bloggers depicted destroyed or damaged Bradley infantry combat vehicles and Leopard 2 tanks, which were the centerpieces of Western military aid for the counter-offensive.
Muzyka estimated that Ukraine may have lost up to 15% of its Bradleys and a small percentage of its Leopards, though it was conceivable that Ukrainian forces had recovered some of these vehicles and sent them for repair.
Jack Watling, a military analyst for the RUSI think tank, opined that it was too early to determine whether the offensive had succeeded.
"We must refrain from premature pronouncements of success or failure," he said.