First of all, if a war is going great, you don't need a diversion. Let's just put this out there now
Secondly, if Russia is behind this, when Israel done dealing with this Gaza saga, they will turn to Ukraine, and beside the US, Israeli is the only other country that have tons of surplus article, expertise and know how to train the Ukrainian on how to use this, also don't forget roughly 18% of Ukrainian are Jew, that mean there may be a chances that Israeli is going to be directly involved in that war. If mean if this is actaully Russia doing and Israeli know? I mean Israel is willing to level Gaza like this, it won't end well for Russia if they know Russia is behind this.
As for whether or not US can support both Israel and Ukraine? Why not, it's not like US is giving the same thing to Israeli and Ukraine, US is going to give a lot more Aerial Asset to Israel (F-16, JDAM, F-35), while US is giving Ukraine older ground asset (HIMARS, Abrams, Bradley and so on) what Ukraine need Israel has a lot, what Israel need US is not giving any to Ukraine anyway, In fact, what do US need to give Israel to execute this war? Unless you are talking about an Arab alliance attack on Israel, US probably not going to need to do anything other than parking Carrier Group in the Med for deterrence. It would be naive to think US cannot support Israel and Ukraine at the same time, given US support to Ukraine is very small.
On the other hand, what advantage the Russian is getting over this? It would be a lot more logical if Russia is indeed behind this, they ask Hamas to join the fight in Ukraine in exchange of official support of Palestinian independence, I mean at least this way you get thousand if not hundreds of thousand free fighters for your war, instead of asking them to die for theirs. The war is blogged down for Russia already, I mean they didn't make any progress for the 10 and a half months in 2023, and it will not be any progress unless they do another general mobilisation. So literally if Russia is behind this, it gains nothing from this, and while asking hundred of thousand people to die for this? That is beyond desperation.