Taking the question in good faith It would have to match or exceed what the IDF are doing to Palestinians and they would have to be a serious threat, because right now, the status quo is such that for the last half a century the injustices are almost universally one sided. The conflict as a whole is completely fecked, and nobody comes off well, the british included. But this isn't a situation where you can pull the "both sides" card in my opinion, political violence and war are a shit reality of the world until we get to some post scarcity utopia, every change in our history has come about as a result of it, and not all forms are equivalent. Hamas firing rockets and killing the occasional Israeli civilian is terrible, and you can argue quite well, that its not effective and counter intuitive, but the burden of that retaliation doesn't solely rest on Palestinians in gaza, what are they supposed to do they've tried everything else for decades? It's also clearly not a credible threat, its a cry for attention, Missiles that actually get through are incredibly rare and they get pinged out of the sky almost immediately.