They sadly feel they can do what they want and that's probably true within reason. Iran isn't getting involved because the US is right there and they don't want to be bombed and have to deal with getting into a long-lasting war any more than the US does at this point. Same with other regional powers. They make statements in support of Palestine, draw red lines, and then yank the lines back a little when Israel toes up to them. They'll allow Israel to make certain shows without reacting with violence because none of the players in that region wants the regional war they can all see happening if they jump in against the zionist occupation.