Don't be like the Palestinians
Extra-judicial slayings are the purview of the Palestinians and shouldn't be the modus operandi of the Israeli army. Just as we shouldn't have been torturing terrorists and stoop to their level, the Israeli army should behave professionally even in the face of such atrocities committed by Palestinian terrorists.
But let's be clear. The difference between the Americans and Israelis and the terrorists is that these ugly situations are the exception rather than the rule.