This has devolved into a bloody static war that will grind on and on. Ukraine is running out of troops. That is math. Russia is already deep into its reserves regarding equipment and has decimated their NCO and young officer core. Russia is almost to the point that they are going to have to make hard decisions regarding the North Caucasus's and the other far-flung satellite states. They cannot "govern" by force in these outlying regions while also heavily conscripting from there for the front lines. Russia is trying to balance not conscripting heavily from the "ethnic Russians", which is unpopular, while not upsetting the satellites by wiping out an entire generation of men as fodder. This is a recipe for political unrest and Russia knows this. They have "access" to manpower, but each year the political cost becomes that much greater, and they are one misstep from having another Chechen War-style headache far from Moscow.
With China and Iran not able/no longer willing to provide drones and high-tech munitions, and most of the Arab world not wanting to get involved with "Russia's war" after the fall of Syria and Iran, Russia has limited options other than the continued slow grind on the ground. If Ukraine can begin the target deep behind the Russian lines again with advanced ordnance (and more importantly US intelligence), even the current slow grind by Russia is impossible. So then it becomes, much like the static lines of WWI, where inertia and pointless loss of life were commonplace. Both sides will then need come to the realization that true gains are unlikely and a continued, never-ending drain of political capital is the likely outcome.
This announcement should not be a shock after we saw reports of a HIMARS strike to kill the command staff of the 155th brigade in Kursk a few days ago. The only way HIMARS works is if the US allows the systems to target. That is only done with US "supervision" and with full US knowledge and blessing. I would also bet that the intel used to select and find this target was US-generated as well. When was the last time there was a well-publicized HIMARS strike? One in June, hitting a troop convoy, and one in March hitting some helicopters on the ground. This is a whole different level of target and intel needed. This US public proclamation of wanting to send "defensive" weapons goes along with the implied threat from the HIMARS decapitation strikes, and both are there to try to get Putin to get back to the negotiating table. Expect to hear discussions regarding additional sanctions regarding Russia coming from the US State Department as well, if Russia does not "get the hint" to apply even more internal political pressure.