Maybe pro-Palestine marches have potential in Europe. This has not been the case in America. In Chicago, pro-Palestine protests drew huge crowds a year ago (I didn't photograph the crowd size, but it was maybe 5k+ people and several city blocks long when marching). They were held every weekend for months. The accomplishment: City Council passed, via narrowly choreographed vote, a symbolic resolution supporting a ceasefire. No banning of weapons manufacturers, no BDS legislation, nothing real. By late 2024, marches have dwindled to the same 300-500 lefties all trying to get new blood to join their party, with perfunctory police presence since they don't pose a threat. I don't have a coherent theory of when peaceful protests are a useful weapon and when they are not. Maybe a demonstration, saying "hey we have thousands of organized people and although we're peaceful today we won't be if you don't meet our demands", would be powerful. But without an organized left that's an empty threat; in the US, protests largely serve as a pressure relief valve. Activists say that you can use the "momentum" of protests to make material change. But that's shown itself to be false for 60 years - if a protest movement has no potential unless it redirects itself, it has no "momentum" to redirect. Joining a crowd of strangers doesn't build solidarity or community any more than Lollapalooza.

There are some losers who might go to riots and solidify what they are starting to believe (I did in 2020). But overall, as workers develop class consciousness, they will search for methods that work. They want to fight for real. In the US, we've seen protest movement after protest movement come and go; anybody paying attention knows that going out in the street to shout at cops doesn't get anything done. I think the intermediate steps between 0 and sabotaging weapons factories have to be actually-meaningful small wins. In the US, that is probably workplace organizing. For instance at my last job I got everyone to agree not to accept Israeli VC money. Lots of unions have put forward pro-Palestine resolutions of various strength, and UAW did some political strikes in California. The next steps would be, as you said, collective workplace actions that materially oppose the war like refusing to ship weapons.

There are some protests that might work as stepping stones. For instance, the Animal Rights Collective in Chicago (part of CAFT) has been doing small protests in front of clothing stores, only going away once the stores promise to stop selling fur. That works, albeit slowly, but these protests attract only a couple dozen dedicated activists. It's the way an already-existing organization exerts force, not a mass tactic that will grow the organization. The reason is because these protests are "inefficient": they don't actually make use of the participants' power as workers. It's just brute force of determination; there's no path for mass growth.