OK. Air supremacy has been key to this war, as in most peer wars. The Russians initial charge was snuffed out because largely because the Ukrainians' Stinger missiles prevented any close air support. That has not changed. What has changed is both Russia and Ukraine are now using the tactic of long-range glide bombs - the Russians much more successfully in part likely because Ukraine has just recently started receiving them from the West. These glide bombs allow Russian fighter/bombers like the SU34 to release them 70 kms away. As a result, Russian troops have been able to achieve localized air superiority and advance in places like Avdiivka because they concentrated their glide bomb attacks (100+sorties/day) on one small geographic location. Ukraine has countered these glide bomb attacks by bringing their Patriot Missile batteries up closer to the front lines - and this tactic clearly worked - with Ukraine knocking out roughly 1 fighter/bomber per day over the course of 2 weeks. Such losses are completely unsustainable by the Russians. But, Russia countered by finally locating 1 or possibly 2 of these now vulnerable Patriot systems and took them out.
Solution?
IMO providing Ukraine with our more advanced Patriot missile batteries (with a range of up to 100 *miles*) would stop the Russian glide bomb tactic in its tracks. But this risks our more advanced technology ending up in Russian hands. And the cost. And the extent of our reserves. And it gives Ukraine the ability to really, really **** with Russia deep inside their Motherland, which could have other political implications.
There are numerous other weapons systems we have in stock that could turn the tide of the war, but the fact that our 40+ year old technology that we've provided Ukraine to date has basically bled Russia to death is telling: We are light-years ahead of them in most technologies (hypersonic abilities aside) and Putin is painfully aware that should he push the tactical nuclear button, the West would be compelled to (right or wrong) enter the war. The end result would be an annihilation of Russian troops in Ukraine, and likely the overthrow of Putin at home. These are events that, seemingly, our government really doesn't want.