I sometimes wonder if there’s a sort of chain shot one can toss at a flag to instantly tear it to shreds, like a ship’s sail but much smaller. Probably not, though, given flags aren’t tied down the same way.
I imagine a paint bomb could be effective for defacing a flag at a distance? Honestly I think James Blitch’s approach of simply lowering it is far more effective though. Especially if you can also remove the ropes. There’s also a brilliant power move if they raised the American flag in the Confederate flags place