The Ukrainian people are being used in a proxy war in an attempt to weaken Russia (eastward expansion of NATO, Maidan coup, reneging on Minsk accords and shelling the Donbass). Hence the shipment of arms to try to keep the conflict going as long as possible, whatever the cost in terms of human lives and economic blowback.
It is about trying to maintain US global dominance against resistance from Russia and, especially, China.
Corbyn had to be destroyed politically because there was a danger (likely minimal in reality) that he might oppose the Atlanticist/imperial/neoliberal agenda if he ever got into power. That was what the antisemitism smears were all about (and, of course, support for Zionist Israel is a mandatory part of support for US imperialism) and the engineered ambiguity about Brexit.
And, of course, Assange has to be destroyed physically for exposing the crimes of empire.
Corbyn should be calling unequivocally for cessation of arms shipments to Ukraine and, yes, a ceasefire, the acceptance of Ukrainian neutrality, and acceptance of the loss of the Donbass and Crimea.
That he doesn't is embarrassing. As embarrassing as his failure to stand up against the weaponisation of antisemitism used against his allies and supporters, his party and, ultimately, himself.