Why does the Biden administration support the Israeli genocide and war crimes even in the face of virtually universal condemnation, at massive expense, and to the point of totally debasing the rules-based international order? Why do it? People fall back on narratives about the power of AIPAC in US elections etc., which is real but also doesn't capture the whole story.

The truth is that US capitalism depends on it, and the US ruling class broadly understands this fact. The key thing to understand is that capitalist growth and accumulation in the imperial core (the US, Britain, Germany etc.) relies heavily on the appropriation of cheap inputs and resources from the periphery and semi-periphery of the world economy (broadly, the global South). They need the South to remain a subordinated supplier within global commodity chains.

In order to maintain this arrangement, it is imperative for them to suppress sovereign economic development in the South. Because the "problem" with development is it means Southerners begin to produce for themselves and consume their own resources. This makes resources and inputs more expensive for the core, which constrains consumption and profits. Economic sovereignty in the periphery threatens capital accumulation in the core.

To avoid this, the core states constantly intervene to prevent or crush any movement or government in the periphery that seeks national liberation and economic sovereignty. The US started to support the Zionist project in the 1960s, and invested heavily in the Israeli arms industry, with the explicit intention of using Israel as a staging ground—a massive military base—for counter-revolutionary interventions against rising Arab socialist and national liberation struggles in North Africa and the Middle East. The US could not accept the prospect of sovereign development in that region: liberation movements had to be crushed or destabilized and they used Israel to help them do it.

Israel is not an "ally" in the conventional sense. It is a proxy. They support Israel for the exact same reasons that they have backed assassinations or coups against liberation leaders across the global South: Mosaddegh, Lumumba, Nkrumah, Allende, Arbenz, Sukarno, Sankara... Israel assassinates movement leaders in the Middle East and interferes in regional political processes, all in concert with the US, but it also constantly bombs the frontline states, destabilizing their societies and economies and forcing them to divert resources toward defensive spending rather than industrial development.

The Zionist project is intolerable not only because it is murderously hell-bent on ethnically cleansing Palestine, but because it creates chaos and instability across the whole region. The core states used South Africa in the very same way. The key reason that Western powers supported the apartheid regime in South Africa – against overwhelming international condemnation – was because it served as a highly militarized Western colonial outpost that was geared up to run counter-insurgency operations not only within South Africa, but also in Angola, Mozambique, Zimbabwe, Namibia, the DRC, etc., leaving immense violence and chaos in its wake.

The vast majority of the world—and international law itself—supports Palestinian liberation, but Palestinian liberation would constrain Israeli power and open the way to regional liberation movements, and this is strongly antithetical to the interests of Western capital. So this is the situation we are in. The Western ruling classes are willing to back obscene violence in Gaza, and shred the liberal values they claim to believe in, because they want to maintain the conditions for capital accumulation and geopolitical hegemony.

You cannot appeal to imperial power in moral terms. The only way the US will stop propping up the Zionist regime is when it becomes too costly for them to do so. This will come down to the strength of the resistance and regional political and military opposition, but also the extent to which people can coordinate boycotts, divestment and sanctions, and punitive measures under international law.

I've used bold text for key points and separated the text into paragraphs for better organization.