The Ukrainian military is doubling down on efforts to break through thick Russian defenses in its counteroffensive in the south, which has struggled to gain momentum since being launched at the beginning of June.
Ukrainian officials have said little about what fresh units are being committed to the offensive, but the military has clearly added recently-minted units equipped with western armor in at least one important segment of the southern front.
The challenges faced by the Ukrainians are perhaps less to do with numbers and more to do with capabilities, training and coordination, factors that are critical when an attacking force is faced with such an array of defenses.
Fragments of geolocated video show that western armor such as Bradley fighting vehicles have been part of the renewed assault and that experienced units have been brought into the fray. But tight operational security on the part of the Ukrainians precludes a full assessment of what is being done to reboot the counteroffensive -- and where.
There's still debate about the size of the additional effort.
George Barros of the Institute for the Study of War -- a Washington-based group -- told CNN: "We had not seen any evidence of a battalion-level attack and certainly no brigade-level attacks. If the Ukrainians are indeed committing full battalions and brigades now as reported, that would mark a clear new phase of the Ukrainian counteroffensive."
A Ukrainian brigade is roughly 3,000 troops.
Mines and more mines
For weeks Ukrainian forces have struggled to break through Russian lines because of layers of defenses: tank traps, other obstacles and dense minefields. According to some Ukrainian accounts, they have resorted to using small groups of military engineers working through forested areas to cut a path through or evade these minefields.
But navigating them will not break the back of Russian defenses. Satellite imagery shows multiple layers of Russian fortifications, sometimes 20 kilometers deep: breach one and another awaits.
Despite hurried training, some of it in western Europe, Ukrainian forces appear to be struggling to carry out combined arms operations: the use of multiple different assets to suppress and degrade Russian defenses both in the air and on the ground.
"Russian attack helicopters and fighter-bombers are exploiting weaknesses in Ukraine's air defenses, enabling the Russians to strike Ukrainian ground forces. Conducting a mechanized penetration of this magnitude while the adversary has air superiority is extremely difficult," says Barros at the ISW.
"Operations are more sequential than synchronized," says analyst Franz-Stefan Gady after a visit to the front lines and extensive conversations with the Ukrainian military.
"Ukraine will have to better synchronize and adapt current tactics, without which western equipment will not prove tac[tically] decisive in the long run. This is happening but it is slow work in progress."
Gady says that in addition, Ukrainian troops he spoke with "are all too aware that lack of progress is often more due to force employment, poor tactics, lack of coordination (between) units, bureaucratic red tape/infighting, Soviet style thinking etc."
He says that makes the Ukrainians more vulnerable as they try to advance, and there is some evidence of that in the few videos that have emerged on social media.
"It's not just about equipment. There's simply no systematic pulling apart of the Russian defensive system that I could observe," Gady tweeted. "Weakening Russian defenses to a degree that enables maneuver," which will include the use of cluster munitions, is a critical task in the weeks ahead.
The commitment of new units this week does appear to have enabled the Ukrainians make modest advances south of the town of Orikhiv, edging closer to the important Russian hub of Tokmak some 20 kilometers to the south of the current frontline.
There are other modest successes further east, but the few frontline accounts to have emerged speak of unceasing Russian aviation and artillery strikes.
Kostyantyn Denysov, a member of the Freedom Legion, said the fighting was relentless.
"In a word, it's hell," he told RFE/Radio Liberty this week. "There are small arms battles along the entire contact line, counter-battery fighting."
"Their helicopters are flying here in pairs and shelling our positions, Su-25 assault aircraft are working, dropping bombs on our guys' heads. Many units have been brought here to try not only to stop our movement, but also to recapture lost positions in certain areas."
The Ukrainian military's critical need is to gain momentum - and force Russian commanders to make painful choices about where and how to deploy their units.
It is far too early to tell whether the Ukrainian counteroffensive has entered a more dynamic phase. The ISW cautions that "this kind of penetration battle will be one of the most difficult things for Ukrainian forces to accomplish."
Nor can the Ukrainians focus their entire effort on the south. The Russians still hope to make tactical advances of their own in the north and eastern fronts, so the Ukrainians have to retain substantial and capable forces along the straggling northern front.
As former Australian general Mick Ryan writes: "General Gerasimov, who we assume retains overall command of the Russian special military operation in Ukraine, is implementing a defensive strategy. But concurrently he is conducting offensive activities at the tactical and operation levels," especially along the front that leads north from Kreminna to Kupyansk.
The Kremlin has seized upon the slow progress of the Ukrainian counter-offensive: a rare opportunity to go beyond damage limitation.
President Vladimir Putin said on July 21 that it was "clear today that the Western curators of the Kiev regime are certainly disappointed with the results of the counteroffensive that the current Ukrainian authorities announced in previous months."
But this conflict has been a graveyard of premature declarations.
There are factors that may work in Ukraine's favor.
George Barros at the ISW says the Ukrainians may be able to exploit geographical advantages.
"Russian defensive lines are not all contiguous or uniformly suited for strong defence. Some lines are bisected by water features or difficult terrain. Some lines are arrayed in such a manner that it could make a controlled withdrawal from one prepared defensive line to the other difficult."
Pointing to successful Ukrainian attacks along the Mokri Yaly river, Barros says that "many such exploitable terrain intricacies exist along the southern frontline."
Russian units are suffering battle fatigue, with insufficient rotation or relief even as reinforcements are brought forward. Elements of the 58th Combined Arms Army have been fighting in Zaporizhzhia non-stop for nearly two months.
Its commander, Major General Ivan Popov, was dismissed earlier this month for complaining to the Russian Defense Ministry about the situation.
Most observers say that in contrast, Ukrainian morale remains robust.
Even so, Gady contends that "Russian forces, even if severely degraded and lacking ammo, are likely capable of delaying, containing or repulsing individual platoon- or company-sized Ukrainian advances unless these attacks are better coordinated & synchronized along the broader frontline."
The long road
Some Ukrainian officials have complained that allied expectations have been unreasonable given the depth of Russian defenses and Russian air superiority -- and the speed with which they have had to stand up new brigades.
While grateful for Western equipment such as mine engineering vehicles and cluster munitions, they say much more is needed. F16s would neutralize Russia's air superiority; longer-range artillery would accelerate the damage to the Russian military's logistics.
Absent an unexpected collapse of Russian lines, Ukrainian gains "are likely to occur over a long period of time and interspersed with lulls and periods of slower and more grinding efforts as the Ukrainians come to successive Russian defensive lines and themselves require relief and rotation," says the ISW.
Gady concurs. "I suspect this will remain a bloody attritional fight with reserve units being fed in incrementally in the coming weeks and months," he tweeted.
If that is the case, and this conflict begins to resemble the static frontlines that began to solidify in Donbas in 2015-16, when Russian-backed forces captured Ukrainian territory, other questions arise.
Will western governments begin to exert pressure on Ukraine to seek a settlement? And given the losses suffered thus far, Russia's ability to generate reinforcements and the uncertainties surrounding the US presidential election - will the Ukrainian government's own calculations shift?