Delays in Western weapon systems slowed Ukraine's counter offensive

 ISW:

Delays in the provision to Ukraine of Western long-range fires systems, advanced air defense systems, and tanks have limited Ukraine’s ability to take advantage of opportunities for larger counter-offensive operations presented by flaws and failures in Russian military operations. Western discussions of supposed “stalemate” conditions and the difficulty or impossibility of Ukraine regaining significant portions of the territory Russia seized in 2022 insufficiently account for how Western delays in providing necessary military equipment have exacerbated those problems. Slow authorization and arrival of aid have not been the only factors limiting Ukraine’s ability to launch continued large-scale counter-offensive operations. Factors endogenous to the Ukrainian military and Ukrainian political decision-making have also contributed to delaying counteroffensives. ISW is not prepared to assess that all Ukrainian military decisions have been optimal. (ISW does not, in fact, assess Ukrainian military decision-making in these updates at all. Yet, as historians, we have not observed flawless military decision-making in any war.) But Ukraine does not have a significant domestic military industry to turn to in the absence of Western support. Western hesitancy to supply weapons during wartime took insufficient account of the predictable requirement to shift Ukraine from Soviet to Western systems as soon as the West committed to helping Ukraine fight off Russia's 2022 invasion.

The military aid provided by the US-led Western coalition has been essential to Ukraine’s survival, and this report’s critiques illustrate the importance of that aid as well as its limitations. Western military advising before the February 24 invasion helped the Ukrainian military resist the initial Russian invasion. Western weapons systems such as the Javelin anti-tank missile helped Ukraine defeat that onslaught and throw the Russian drive on Kyiv back to its starting points. The provision of essential Soviet-era weapons systems and munitions by members of the Western coalition has kept the Ukrainian military operating throughout the war. The delivery of more advanced Western systems such as the US-produced 155mm artillery (in April) and then HIMARS (in June) facilitated the Ukrainian counter-offensives that liberated most of Kharkiv Oblast and then western Kherson Oblast.[1] The arrival of Western NASAMS air-defense systems in November helped blunt the Russian drone and missile campaign attacking Ukrainian civilian infrastructure.[2]

The war has unfolded so far in three major periods. The Russians had the initiative and were on the offensive from February 24 through July 3, 2022, whereupon their attacks culminated. The Ukrainians seized the initiative and began large-scale counteroffensives in August, continuing through the liberation of western Kherson Oblast on November 11. Ukraine has been unable to initiate a new major counter-offensive since then, allowing the conflict to settle into positional warfare and allowing the Russians the opportunity to regain the initiative if they choose and to raise the bar for future Ukrainian counteroffensives even if they do not. The pattern of delivery of Western aid has powerfully shaped the pattern of this conflict.
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The current stalemate is similar to that in World War I which lasted until tanks were developed along with the delivery of fresh troops from the US.  What we have learned so far in this war is that western weapons such as anti-tank weapons and Himars were effective in blunting the Russian's initial campaign. Those along with the supply of Soviet-era weapons in the stockpile of former Russian allies were enough for the initial counteroffensive.  Now getting the tanks into Ukraine and preparing the Ukraine military for their operation and use will decide the effectiveness of any continued counteroffensive against the Russians.  

It should be noted that the Russians are also struggling to replace their tanks and other mechanized units lost early in the war.  They have responded to that with meat grinder attacks where their troops and mercenaries have suffered significant casualties. The Russians have been pulling older tanks out of storage to deal with their shortage, but I suspect they will be even more vulnerable to western anti-tank weapons.

See, also:

Thanks for Lend-Lease: how trophy Russian equipment is attacking occupiers

 The Ukrainian military has captured a lot of military equipment from the occupiers, which they are using to destroy their positions.

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The T-90 tank, which was fairly taken from the Russians in April in Sumy Oblast, was developed back in the days of the Soviet Union. This is a modernisation of the T-72 Ural tank, which was used during hostilities in Syria, Iraq, Sudan and a number of other countries.

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And:

 Russia Is Refitting Old T-72 Tanks For The War In Ukraine. But It’s Running Out Of Optics.

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The result is at least one new T-72 model: the T-72B3 Obr. 2022. It’s a 1980s-vintage T-72B with a suite of enhancements including a Sosna-U day-night digital gunner’s sight, new reactive armor, a rear-looking video camera and a fresh barrel for its 125-millimeter main gun.

Don’t get too excited. The additions don’t significantly improve the T-72’s performance—and don’t do anything to remedy the type’s fundamental problem: its dangerous ammunition stowage.
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And:

 Crimea is shaping up to be the battleground that will decide the Russia-Ukraine war

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 "The decisive terrain for this war is Crimea. The Ukrainian government knows that they cannot settle for Russia retaining control of Crimea," retired Lt. Gen. Ben Hodges, a former commander of US Army Europe, told Insider.

"The next few months will see Ukraine setting the conditions for the eventual liberation of Crimea," he added, emphasizing that the country will "never be safe or secure or able to rebuild their economy so long as Russia retains Crimea."

Russia occupies Crimea and a significant swath of southern Ukraine — including the cities of Melitopol and Mariupol — that provides it with a land bridge from its own border to the Crimean peninsula. This area serves as a pivotal supply route for the Russian military. The peninsula, roughly the size of Massachusetts, is home to a number of military bases and Russia's Black Sea fleet.

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And:

Russia was making big plans for Ukraine's nuclear power plants before its invasion fell apart 

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First, Moscow planned for Ukrainian nuclear power facilities to function as bases for Russian troops and their equipment as well as ammunition depots. Russian officers were also to set up command-and-control posts within the premises of those nuclear facilities.

The second function the Kremlin envisioned for the nuclear facilities was to gain control over Ukraine's energy system. Nuclear power generates more than 60% of Ukraine's electricity. Thus, by controlling the nuclear facilities, Moscow would have influence over Ukraine's population and economy.

Finally, Moscow wanted to control the Ukrainian nuclear facilities so as to have "leverage for blackmailing" European countries. By threatening Europe with radiation pollution from potential accidents, the Kremlin hoped to deter direct or indirect foreign intervention.
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