Not only would I be advising Burnham to cease arm sales and supply with immediate effect.
I would be going for complete sanctions against the state, similar to what most of the world imposed on South Africa during Apartheid.
So full economic and trade sanctions.
Closing the Israeli embassy and the expulsion of their ambassadors.
Legislating to ban Israeli lobbyists and money from UK politics. Although that would mean an internal war with Labour Friends of Israel. A fight long overdue.